AD&D is not even remotely lightweight and there's much better organisation for PBTA games in general than anything D&D
I don't know why you assume I'm talking about AD&D... I don't like it as a system and I find it's online culture tends to attract the worst of the old OSR these days (which is sad for the decent folks who just like the game) ... but I don't play it precisely because it feels fiddly, excessive and ill assembled from half complete Strategic Review articles to work as a court exhibit. So AD&D is too much, especially for what one gets in return.
I'm an OD&D player by choice - the LBBs from 1974 with house rules, something that makes the char gen of B/X look complex. This is part of why I like it. B/X and it's pack of retro-clone spawn are also perfectly fine with me for a Dungeon Crawl game, and very quick to set up as well. The only complex game I have any interest in running these days would be something like Pendragon (though Mythic Bastionland is more interesting to me right now) and I would say it's something that benefits from a longer character building process.
However, my point here is not that quick set up games are superior to slow ones, but that not everyone wants a slow character build game, even if there are plenty of people who do ... and that some games and play styles lend themselves to slow or fast set up based on things they want to do and what sort of play they want to emphasize.
If I want this then I'll start a 5e game (or a Daggerheart one) before you've even started your AD&D one. That's because I teach newbies and sometimes open campaigns by using level zero characters with default assumed stats of 12 and we'll sort things out in play. No emails needed and everyone will earn their class in play.
You seem sort of mad at this AD&D referee? It's not me.
I have to shrug at your fix for complex chargen games here though ... Pregens are of course always an option. They're an option for this AD&D referee who wants to do quick starts as well, and doing so has been popular since the late 1970's in the form of "tournament games" and is arguably one of the intended purposes of AD&D. I personally like emails because I play online mostly and it give players a chance to ask questions at their own pace directly of the referee so if you have a player who is really squicked out by spiders or doesn't play with another player since "the incident" or something they can tell the referee without getting the whole group involved. For a public game one can do most of the same in 5 minutes.
Yup! Different groups want different things - and I find Session Zero goes with high inter-character RP groups.
Agree, it's a thing some people like - but it is not universal and not a necessity. That is works well for some kinds of games, and not others is precisely my point here.