Imaro
Legend
So D&D now delivers a wider range of possible adventures, right? A greater number of experiences (adventures) versus a core experience (site-based exploration).
I think so but I think (because some of these I wasn't old enough to play when they came out) the only edition of D&D that ever focused solely on site-based exploration was possible OD&D? BECMI took you beyond site-based exploration with Expert/Companion/Master/Immortal. AD&D 1e had the Wilderness Survival Guide, AD&D 2e had too many settings/adventures outside the realm of site-based exploration for me to list. 3e had rules beyond site-based exploration as did 4e and 5e. So when you say "now" do you mean starting in the 70's/80's?
Does that wider range require a greater number of structures to help deliver those experiences?
While certainly a possibility... I don't think that's a requirement. You can have a general structure which the DM then uses as a basis to extrapolate for other situations. As an example the skill usage structure can be applied across numerous situations.
Has the game delivered that? Are the suggestions in the DMG on how to do these things sufficient?
I can only answer for myself...Yes and yes (with the caveat that the "game" encompasses more than the DMG). I have been running 5e for years now and there hasn't been a situation that arose where I was at a complete loss on how to handle it. The game has, IMO a robust structure around combat and magic, as well as a suitably flexible structure concerning skill usage along with enough suggestions in the DMG and supplemental material that I would argue it's sufficient for the vast majority of things that arise... Though admittedly said answers, suggestions, etc. may not suit everyone's particular tastes.
Does "the GM gets to decide" suitably replace any and all such structures?
If we consider "GM decides" as a structure, then aren't all games that follow that structure similar in the same way as all site-based exploration games are similar? Have we simply replaced one core experience (site-based exploration) with another (GM's-fiction exploration)?
Nope... since individual GM's will decide how to implement their structures differently.
Not solely, no, but I'd say it's a big factor. Take a player from Critical Role and have them jump in on Dimension 20, and they'll hit the ground running. Take them and put them into a B/X game and they'll need some adjustments.
Though I don't know if this is actually GM style... as @Vaalingrade pointed out, Dimension 20 is more madcap than Critical Role. That's more a tonal difference. And there are differences in genre between the two, as well. Those seem more about style.
What I'm talking about is the actual structure of the game and how it works and how I as a player experience it.
This seems to be implying that rules differences are the determining factor? So would you agree to the statement that all PbtA games feel the same? What about FitD games? If not... what's the difference?