In retrospect the Dream Park parties, usually a large crew of players led by a Loremaster, kind of remind me of late-70s era D&D tournament play/modules. Where the modules often had a suggested group size of 8-10 players (some tournaments got as big as 12), and a Caller was actually a useful thing to have for time efficiency.
I'm sorry to say that I never really experienced the "mega-(competition)-dungeon-crawls-at-mega-conventions" that were happening in the US when I started playing way back when. I suppose that, at the time, the people playing (A)D&D in Holland could probably fit on a small stamp and all you could buy product-wise depended on whether the owner of the one shop that sold them had been to the UK or not that year.
Still, never too old to learn and all that and we have been sort of re-living the feeling for the past year in the shape of a seriously old-school random dungeon crawl. Ten PCs, two per player (unheard of for decades) and it is truly exciting to see people constantly on their guard for pit traps and then die from a poisoned needle in a treasure container - to subsequently be resurrected by the 18th-level Cleric with Wisdom 18 in the village nearby, who, of course, only exist for this purpose. I find it fascinating and refreshing to dig into the 1E rules and remember and implement them as they were meant for dungeon-crawling purposes - to walk back along the trail created by the game as it developed. Quirks in the rules are exposed (sages); the excellence of the DMG1 as a work of reference is confirmed again; the pretty coherent mechanics of the 1E game and their basis in table-top warfare shine through; mappers and, as you say, callers rise from the grave.
The PCs are confronted with the fact that everything costs money (and usually A LOT of it); that they must train before they can actually advance in level and get no further XP until they have done so; that they can only die so many times because resurrection has its limits; that jewelry is the thing to find; that "men are the worst monsters" (DMG1, p. 21); that stirges, troglodytes, and even shriekers are to be avoided at all costs at lower levels; that the one-day trek to the village is a serious problem because wilderness encounters do not care what level they are (phase spiders at 1st level anyone?); that dwarves are the way to go for dungeon crawls.
In a sense, it is quite liberating that nobody cares that the local inn has long since become way too small to house the ever-growing army of NPCs required for all manner of purposes (e.g., training PCs); that the village expands with each session to comply with the needs of the party; to put a city "a week's travel from the village" just because the PCs ask about one; to see the "campaign world" grow in reaction to the questions of the players instead of there being one to begin with.
It all leads to many interesting situations and dynamics, perhaps especially so for experienced players and DMs.
Anyway.
Musings.