I survived my first fight with Moder without dying which was also a solo fight. Also was after the H&H update. So don't pretend to speak for a majority off your own experience.

I found Moder to be easier than Bonemass. The fight with Moder stayed around her altar because I forced her to come at me. You don't chase the boss.

Only problem I had was my bow breaking which was easily fixed with a portal I had nearby because of past experience with the prior bosses.