Or--related, I think--if you don't optimize hard, you're not pulling your weight. I honestly wouldn't want to be a play culture like that, at this point.
It is something of a vicious cycle, I think.
1. Optimize character somewhat.
2. Fight things with character (or do whatever that character wants to do, but when talking optimization that's usually fighting).
3. "Huh, that was easy. Make it harder."
4. Fight other things.
5. "Damn, that was hard. I need to up my game." Optimize some more.
6. GOTO 2.
And by the time someone has completed a cycle or two of that, anyone else who wants to play together with that character needs to go down the optimization route themselves. The only four solutions I can think of are:
A. The only winning move is not to play. Don't optimize, and make sure you don't play with people who do. This is a bit hard to do on the game design level, though.
B. Remove most choices from character creation/advancement and limit choices to specific points where each choice is supposedly balanced with other choices. In 5.0, you see this with the Totem Barbarian where (in theory) Bear, Eagle, Elk, Tiger, and Wolf are all balanced against one another, and choosing one doesn't change anything else downstream.
C. Make a super-balanced system where there are numerous optimization paths that all turn out to be balanced with one another. Good luck with that.
D. Balance in chunks. Instead of allowing many smaller choices that may or may not synergize with one another, have characters make fewer but more significant choices, and then it becomes easier to balance those against one another.
5e mostly goes for option D, with few choices to make once you've chosen a class and subclass.