I have no horse in this race, as I'me moving more and more to the "level whenever" camp.
I hate to admit it, but honestly I am too. However, if I am being honest, the only reason why this approach is attractive (to me) is (my own) laziness.
It used to be that you got stuff in D&D because of what you accomplished. Are we at the "participant trophy for everyone" stage now? #getoffmylawn
This is still the way I feel it ought to be done, but it causes so much trouble, between butthurt players and party level disparity, that it is barely worth the effort.
He doesn't mention at all a thing that I believe should be discussed: leveling from 17 to 18 should be as easy as leveling from 3 to 4? I don't think so. But that's certainly the kind of thing that one can easily houserule.
I've always felt that the way experience ought to work is that the level difference between the party and the monster ought to be what determines the monster's XP value, not its total hit dice or CR. So a level 1 party fighting a level 1 monster and a level 16 party fighting a level 16 monster ought to get the same flat quantity of experience points. The quantity of experience required to advance is what increases incrementally as more and more advancement is achieved.
But this is backward from the direction in which D&D has been moving for many years.
I disagree, if you go by that way than the entire point of the game is killing things. Now that might be the ptefered playstyle of some but it's not universal, personaly I'd like to have XP for gold and monsters where you gain more XP through gold than killing things.
I am not really interested in discussing this point, because it is obviously grotesquely contentious and we will find no common ground. But my position on this matter is that Dungeons & Dragons, at is core, is about exploring dungeons, bypassing traps,
dealing with dragons, and gathering treasure. It is /great/ that the system can be stretched to do other things, and I often stretch it myself, but all of those things are icing.
As icing, they should not influence the core rules of the game. Before D&D can be anything else, it must first be a dungeon crawler. Then we can start talking about elven politics in the Gnarley or extended trade missions to Zakhara.
EDIT: I overstepped my position on the monster front -- you don't have to /kill/ the dragons, but you have to engage them in a way that renders them non-threatening for at least the short term.