NurseyFYI, there always has been a 'no class switching' rule but every admin on the site (including me) have been extremely lenient on it. This was to the point where it was practically never enforced. The rule is being enforced much more heavily now due to some pugs lately being complete blow outs from people changing to their main classes. Please do not switch off the class you were picked on.
I 100% agree that there are certain cases in which this is totally unfair like if a high invite scout is added to an offclass they're not as good at and then swap in game with a solly main picked on scout for example, then the game is totally changed and it's unfair cause the other captain can't have the option to pick them either.
However, I think there are also lots of cases in which this is not a big deal at all. For example, if I and someone else are both added on pocket and roamer, and in the pug we decide to switch because one of us prefers pocketing on a certain map or is feeling like roaming, I see no problem in doing this. Given that it's a pug site and its primary focus is fun I think people should be able to swap if they want to but only in cases where it is super obviously an upgrade or makes things unfair that people should be punished. The problem with enforcing this is that it's all sort of subjective to say that x player is a certain level at one class vs another, and I very much do not believe it should be banned altogether. I could be fine with it I guess as long as like the cases of two soldiers swapping roles when they're both added to them, or a roamer/demo added person swapping with another roamer/demo added person cause it's perfectly fair within the picking.