To be clear: A lot of interesting points have been raised here, thanks for that. Glass ceilings, XP not for mundane tasks, but only important experiences, etc., all that is quite interesting to think and talk about, and has done a fair bit to inform my current campaign preparations.
But the "huh, why bother" talk is really starting to go on my nerves. If you don't think about the whole problem complex addressed here, that's it. Don't think about it, that's fine. But please don't post about it either, at least not in this thread. Open another one where you can discuss your style of campaign planning, if you want (but beware, that might end you up thinking about things), but here, my explicit request is to think about the matters of XP for NPC's in one way or another, even if it is "they are all level 1, and the rate of XP gaining is 0".
Thank you.