I found a DH with like 125k health, started him and easily brought him to around 20%, when he suddenly turned on me and did me so much dmg that he forced me to go on defensive and start healing myself. Well a retri pala is not a thing to easily go down, but while I was on defensive he also regained enough of his hp, so we continued on equal terms, and my surprise attack was wasted. His low gear was a thing so I could easily take him down to low hp again, but the dmg he did to me was severe - no matter my gear. Another ally came and finished him off, for which I regret, it was an interesting battle.
In comparison to disc - with my gear I can’t do a thing to him. Nothing, exactly as you said hitting him with wet nuddles.
So yes, some classes are ridiculously OP compared to others. DH’s make a lot of dmg and you as rogue don’t have enough self healing to withstand his burst…and 1v1 sadly it’s very difficult. IMO your best role is support in group battles, but your support can be essential - you will sit for example on a healer and not let him cast. Which might win the battle for your entire group.