That manager advice sound horrible. That is the point of a manager. If you can't trust them with something as basic and important as team interactions, then there is a bigger problem.
What can a manager possibly do in this situation? "Hey, Boss. Everyone on me team is an asshole. Can you fix that?"
If it was one person on the team causing problems, it could make sense to talk with the manager. If the entire team is toxic (or a bad fit for OP), there is little to nothing the manager can do except maybe help OP move to a different team.
Edit: To be clear, I'm not saying it's a bad idea to talk to the manager, unless the manager is one of the toxic team members. But I'm not sure it's very useful, either.
Maybe manager says "So it's not just me thinking that", or "I've noticed guys can be pretty hard on you at times. Since you haven't brought it up, I thought you're ok with it"...
I can think of million other things that might or might not happen.
And I know only one way to really find out - try and see. Are there other ways?
Suppose the manager has those reactions. What then? They'll sit down with the team and have the "don't be mean" talk? I'm just not sure I see that working well. That seems more likely to breed resentment even if it resolves the superficial "combative" behavior.
I'd probably try talking to the individual team members 1:1. As uncomfortable as that would be, I think it is a better bet than having it come from the manager.
Good point. If I am as mature an adult as I believe myself to be, I ought to be able to have a peaceful conversation about this with a couple of coworkers individually. Definitely would be better than putting them on the defensive by sending a manager after them.
If it was one person on the team causing problems, it could make sense to talk with the manager. If the entire team is toxic (or a bad fit for OP), there is little to nothing the manager can do except maybe help OP move to a different team.
Edit: To be clear, I'm not saying it's a bad idea to talk to the manager, unless the manager is one of the toxic team members. But I'm not sure it's very useful, either.