I think part of it is that in o5e, those power builds kinda just let you actually DO interesting stuff. Polearm Master, Great Weapon Master, Crossbow Expert, etc etc all let you feel like you're actually doing something and actually playing into the power fantasy in a way that usually only Casters get in o5e. Wanting to Powergame and Wanting to Have Fun should rarely* overlap because it makes it infinitely harder to deal with powergaming as a result of "Oh this looks cool

" compared to "Oh this will make me win D&D". If any given character can feel fun, effective, and like the result of your choices powergaming is a lot less appealing I think.
*Main exception I can think of is 4e, where a lot of powergaming was based around team cohesion and coordination more than MAKE NUMBERS BIG.