And they are, until they aren't. And I really do mean that in both directions: Much of the time, the simplest, dumbest, most naive solution is 100% fine for realistic load for the forseeable future. And then some of the time it breaks terribly and you do need to spend effort optimizing it, whatever that entails.
To be clear I am not advocating optimizing everything down to the last bit here. Problem here is when THERE IS a need many would not even have a slightest clue where to begin as all those "low level" concepts were relegated into oblivion.
The question rarely asked is, "Can your team go from zero to sixty on this sort of thing when this happens?"
Technically optimizing as you go might be a 'waste' of time, until it isn't, because your team can handle a serious performance problem in days instead of months (or IME, never).
And they are, until they aren't. And I really do mean that in both directions: Much of the time, the simplest, dumbest, most naive solution is 100% fine for realistic load for the forseeable future. And then some of the time it breaks terribly and you do need to spend effort optimizing it, whatever that entails.