The loner ability has a backstory so lets start at the beginning of it which is in the Open Beta. Really its fun just to see where, why, and how it may be useful.
During the Open Beta it came up that there was no way to field single model squads of Classes level 1 and 2 in higher point games. Think the Rambo type concepts of individual skilled models out in the field doing their job. As the size of game goes up, so does the squad sizes.
Discipline in Games and Squad Size
What happens in games is your Discipline determines your squad size. So if you have a discipline of 3 for instance and the game level you are playing allows you to take a squad size of Discipline x2, this gives you a squad size of 2-6 models. So we created an ability that allowed a squad size of 1. Seems easy enough, but......
Took one in-house playtest session to discover that the first thing someone did was bring almost an entire army of 1 model squads, combining into squads when they deemed a benefit and breaking off solo when they found an advantage.
Loner Models Joined up together
Actual example of what happened one late playtesting night-
Consider this; three single model squads join up together and move across the board activating as a single squad and engage an enemy squad in melee.
They win killing the enemy and easily gain the initiative for the next round. His squads were all joined up to get through his early rounds quickly to gain initiative in the following rounds).
Now that they he is going first, he splits up his squad by activating them individually and has each one go different directions exhausting other squads all with a single model's attacks. (current rules are separating a squad can only be done if cohesion is lost, but this was not always the case.). This created havoc as squads following the loner squads were quickly cutting down every one.
Multiple Small Squad Armies
MSS style armies (Multiple Small Squads) A close combat mss style army often tries to take advantage of exhausting enemy melee squads and then hitting them with a full combat situation later during the game round. Its a valid tactic as its outflanking and out commanding the other army, but is extreme when someone has nothing but squads of 1. Its was a little more crazy when they are joining up with other single models and then leaving the squads as need be.
As Cheap Squad to do something before or early game
One model costs less than two and can fulfill a purpose you need. Infiltrating or recon squads sometimes can pull off their ability or purpose with as little models as possible to keep their point costs efficient.
So the current ability allows a model to be on its own, which is really the benefit of the rule during game play. While it might be a little situational depending upon how the faction and classes are built it still allows for one-man squads to hit the field in games where they would not be able to otherwise and use any advantages they can.
For Humanoids, it prevents them from exploiting parts of the Survivalist Branch, which is based around having individuals or small units who do certain specific things.For Biests it does much the same. Loner is one of several traits to wall off a bunch of Class Only traits that are fairly powerful.The thing here is that Loner is not useful, not in the way you're thinking. It's a tool for the designers to limit access to abilities. I imagine this is in response to the way things played out in testing, with hilariously defensive Humanoids and an entire faction of Biest snipers coming to mind as likely offenders.
The loner ability has a backstory so lets start at the beginning of it which is in the Open Beta. Really its fun just to see where, why, and how it may be useful.
During the Open Beta it came up that there was no way to field single model squads of Classes level 1 and 2 in higher point games. Think the Rambo type concepts of individual skilled models out in the field doing their job. As the size of game goes up, so does the squad sizes.
Discipline in Games and Squad Size
What happens in games is your Discipline determines your squad size. So if you have a discipline of 3 for instance and the game level you are playing allows you to take a squad size of Discipline x2, this gives you a squad size of 2-6 models. So we created an ability that allowed a squad size of 1. Seems easy enough, but......
Took one in-house playtest session to discover that the first thing someone did was bring almost an entire army of 1 model squads, combining into squads when they deemed a benefit and breaking off solo when they found an advantage.
Loner Models Joined up together
Actual example of what happened one late playtesting night-
Consider this; three single model squads join up together and move across the board activating as a single squad and engage an enemy squad in melee.
They win killing the enemy and easily gain the initiative for the next round. His squads were all joined up to get through his early rounds quickly to gain initiative in the following rounds).
Now that they he is going first, he splits up his squad by activating them individually and has each one go different directions exhausting other squads all with a single model's attacks. (current rules are separating a squad can only be done if cohesion is lost, but this was not always the case.). This created havoc as squads following the loner squads were quickly cutting down every one.
Multiple Small Squad Armies
MSS style armies (Multiple Small Squads) A close combat mss style army often tries to take advantage of exhausting enemy melee squads and then hitting them with a full combat situation later during the game round. Its a valid tactic as its outflanking and out commanding the other army, but is extreme when someone has nothing but squads of 1. Its was a little more crazy when they are joining up with other single models and then leaving the squads as need be.
As Cheap Squad to do something before or early game
One model costs less than two and can fulfill a purpose you need. Infiltrating or recon squads sometimes can pull off their ability or purpose with as little models as possible to keep their point costs efficient.
So the current ability allows a model to be on its own, which is really the benefit of the rule during game play. While it might be a little situational depending upon how the faction and classes are built it still allows for one-man squads to hit the field in games where they would not be able to otherwise and use any advantages they can.
Thanks Natfka for the explanation.
Ok, thanks for the response
For Humanoids, it prevents them from exploiting parts of the Survivalist Branch, which is based around having individuals or small units who do certain specific things. For Biests it does much the same. Loner is one of several traits to wall off a bunch of Class Only traits that are fairly powerful. The thing here is that Loner is not useful, not in the way you're thinking. It's a tool for the designers to limit access to abilities. I imagine this is in response to the way things played out in testing, with hilariously defensive Humanoids and an entire faction of Biest snipers coming to mind as likely offenders.