I don't find that achieving a "build" is a very common goal for 5E players (mostly because the character generation system is front loaded and shallow). Rather, the difference I see is that many (maybe most) people come into a D&D campaign expecting to be a competent protagonist in a cinematic story. Among other things, that translates to plot armor or at least the promise of a dramatic and meaningful death.That the goal isn't actually to "win" or "complete your build". The goal is to collectively share an experience, and that this experience becomes richer, not poorer, if it not only contains triumphs and successes, but setbacks and losses as well.
Which is fine. People should play how they want to play. And 5E is made for that kind of game. Go nuts.
But if someone goes into DCC or Shadowdark or OSE expecting that, they are going to suffer a disconnect between their expectations and the system.
The reverse is, of course, true as well. Trying to use out of the box 5E for an old school style game is the wrong tool for the job.