DMsGuild is such a game changer that I'd hesitate to compare it directly: the cultural and economic context is radically different. I wouldn't say that what 2E era TSR was putting out was necessarily more polished game content than much of the DMsGuild.Sort of, yes. But again, some of the specifics I mentioned were lacking: setting supplements beyond a very few, and the same kind of branding of distinct product lines. There were Greyhawk adventures, the DL series, a few odds and ends, but not really "setting product lines" in a meaningful way.
Yes, but they aren't "supported" in the same way, unless you consider DM's Guild support - but that is really just crowd-sourcing. Most of them are one-and-done, with a few having an adventure added on.