An underlying -- perhaps the motivating -- issue in that other thread was the perception in some quarters that characters in 3E gain levels faster than in 1E. Quasqueton's analysis, within the scope of what it covers, suggests that level gains (within that covered context) should be about the same until roughly what would be "name" level in AD&D.
So, whence the perception? There is anecdotal evidence that many DMs skimped on treasure XP, which became standard, "by the book" practice in 2E. In the absence of an adequate replacement, that certainly would tend (perhaps by intent) to slow advancement!
The question of how much potential treasure was likely to be secured by a given group of characters was raised. I don't think that is likely to be a big issue in consideration of most modules, but it could be in a different kind of situation -- such as the dungeon as originally conceived and presented.
That's a situation pretty well designed not to get "cleaned out" by any particular group of characters. As a consequence, it does not lend itself to calculations on that basis (double or triple XP needed to "level up" a party being a good start in my experience, more depending on actual traffic). Moreover, returns per hour of play time may well be lower.
Rapid or slow, a rate involves a component of time. That could be measured in "modules" if they are employed, but to assume that (as opposed, say, to game sessions) as the common measure should have some warrant.
I did not claim to know whether (much less that) most people -- or even any of the people in question, the ones claiming swifter advancement early in 3E -- were playing mainly in scenarios after that model.
(Silly me, I think it might be more illuminating to ask them about their practices rather than getting into vain speculation and assumptions!)
Someone started to claim that the underworld of many ways was not a significant part of the game as Gygax designed it. I can see how the concept might be obscure if one were informed only by select later texts, rather than by the seminal work (even at a remove via oral tradition). It seemed perfectly clear to me, and apparently to plenty of others in the 1970s, though, and nothing I have encountered since of Mr. Gygax's writings suggests to me that this was a misunderstanding.
Then someone else, who seems quite often to indulge in creating false dichotomies, took up the notion that the presence of multi-level dungeons in the original campaign concept was somehow incompatible with the presence of other elements.
Absurdity aside, all that was quite irrelevant to the topic of that thread.
The relevance here is that I find it a bit tiresome to be misrepresented by others. I do not very much like being set up personally as a straw man. I can speak for myself, and trust that those others have enough to say on their own account.
Quasqueton compared 1E and 3E characters in 1E modules. That is not the same as comparing
-- 1E and 3E characters in 3E modules;
-- 1E characters in 1E modules and 3E characters in 3E modules; or
-- characters of any rules-set in a much less linear scenario than offered in most modules, with characters in the latter.
Size certainly can contribute to non-linearity, but a huge complex is not necessary. A dungeon map is pretty handy for analysis, providing a "flow chart" of the sort one might make for any scenario in which players have choices of taking different directions (in events, even if all acts take place spatially within a single little room).
