I think 5e is actually a poster child for the kind of problem I've been talking about. It's built solidly on the foundations of 3e and 4e in terms of having character generation based on a giant menu of competing rules packets, and of combat focusing on efficient use of those abilities and exploiting the action economy.
Now, it's much less broken than 3e was, and there is also much less of a delta between characters built knowingly and characters built naively. But the delta is still there and there is also a big distorting effect in the kinds of characters that see play. How many fighters and barbarians aren't great weapon masters or polearm masters? How many ranged attackers aren't sharpshooters? How many warlocks don't rely on eldritch bolt? How many non-typical class/race combinations really see play? Do all the backgrounds and feats see a broadly equal amount of play?
3e has all these things much worse, and maybe 4e did as well. But 3e and 4e were at least built around them. You could see that 'building an effective character' (3e) and 'giving yourselves a viable package of abilities to play combat scenes effectively' (4e) are at least fun. 5e has all these legacy things of choosing this feat or that feat and choosing this action or that action but the consequences of defeat are so softened, the tactical options so limited, and the focus of the game so diffuse that they are sort of vestigial, artefacts of a previous version of the game that wanted you to think about them rather than taking them for granted as 'how D&D is supposed to be'.