There are good ways to counter a lot of these things, I can state weaknesses.

WARs benefit if the enemy team is stuck together, if they are spread apart WAR's utility is as good as useless thanks to Purify.

NINs have insta kills but they can't deal that much damage by themselves, they are heavily reliant on the team to dish some extra damage. So just don't be complacent about your health when a NIN's LB is up, one recuperate and their plan is foiled.

RDMs have the damage but they can't guarantee kills. White form means they will delay a fight? ignore them. Black form means they will do damage? Focus them down.

AST I never seen much of honestly, so I am not sure. Their CC is annoying but much like WARs need the enemy to be stacked together.

MCH has a bunch single target damage, issue? Whats the point of damage if you can't guarantee kills or lack AOE. Sure their Analysis + Drill, LB combo will take down someone, but I have another class that can confirm kills easier. BRD, yeah, I have a oGCD silence to stop people from healing, no one talks about that.

SAM... Yeah no fuck that they are OP af, but there ways to counter them. Like WARs once again, their Kaiten abilities need the enemy to stack together. Survive past their Midare + Ogi, you can pretty much ignore them for quite awhile, each is 20 secs so they are not going to do much to you until it comes off. Chiten is a 5 sec defensive that has a 30 sec cooldown, once you know its gone you can breath easy for 30 secs (I hope you guys look at the party list for buffs and debuffs), also bind shuts down Zantetsuken. Another weakness, its a god damn melee, it does to be in front of someone to deal damage so mark them and make sure everyone is hitting him, while making sure you all practice safe distancing.