I think part of this is coming from the fact people were lacing into you about being allied, I know we briefly talked about this last night.
Call me old fashioned but I am side dedicated, if I ever switched it would be at the end of the current campaign whether we win or lose but I don't see that happening. That said squads should make it known if they are side dedicated that way new players know the rules. If they break the rules they get a warning, if they repeat they get booted, this is the way it was when I first started playing over a decade ago and it built a cohesive group as a result. Everyone didn't different tasks, we worked with HC to do the things they need to attack or defend which involved the boring stuff like FB defense, but that is what real war is like, there are lulls.
The worst of what you mentioned is being mean to green tags, I have not seen it, but if it is happening they need to stop it not only because we need new players but because it is just rude in general. You can get absorbed in this game and people forget how it was when they first started playing, they need to put themselves in their shoes and help. Last night there was a green tag following me around and he was constantly exposing himself, I had to explain to him how to move up and get good cover and be patient, he wound up getting some kills and had fun(as far as I could see). This game needs to appoint a WW2 online squad that specifically takes green tags and teaches them, you have to get their confidence up in order to turn them into long term players that will spend money.
I hate to sound like an old man who reminisces about "way back when" but it is hard not to when you see how unorganized the game has become from what it used to be. When I first came here people always asked if you would like to join their squad, they would take you to the training server and teach you, you got on TS with like 15 others etc. Everyone was in a squad and the game was packed with them and they were side dedicated and you saw that with the banter on the forums. More than anything I would love to have that back because that is what made this game great, I could log on at any time and the map was hopping.