One might say today what with the numerous ways that one can play the D&D game that its base understanding and thus vision derived from 1972-1976 has been flattened to an all inclusive view of "that's what it is for us now."
Let's Track This Beasty--
1) RPG is invented! There are no books. No modules. Everything has to be created. TSR Rules sells up to 10,000 copies of D&D and there are no adventures then, only what people (DMs) are creating--megadungeons, etc.
2) Geomorphs are envisioned. Booklets of Monsters and Treasures. (Still keeping with the support approach to the original vision of self-created material, but with some published boosters to aid with that). A book of monsters is conceived! (Ever wonder why the Monster Manual preceded the PHB and DMG?) Examine the mindset here. It is rapidly shifting with a sudden realization curve taking effect, sometime after the release of "Palace of the Vampire Queen." Judges Guild starts its rumblings, following suit. More realization. The sounds of cash registers ringing? The hearty throngs coming to the voided well of creativity and moaning? Their silent appeal being met?
3) And then there were ALL. Diversity is good... Now there are pre-made adventures, flying off the presses like pancakes. Role Aids breeches the scene. More for everyone... Tourney adventures... AD&D and the RPGA. And the band played on... (just a little out of step and out of tune)
4) The visionaries leave the band... TSR's marketing kicks in, doubling output. Here, you editors, you write this. We'll slap a fun picture on it and market it to death. Random House will never know the truth....
5) TSR markets itself into 30,000,000 dollars of debt while on its "publishing this and that merry-go-round". WotC buys the band's songs and promises to re-release the album!
6) WotC reinvents the wheel. The songs are remixed and the band members are not invited to help, for how could they? They are from the OLD 8-track and cassette age and this is the NEW CD/DVD mindset leading the way into the cash-cow future. Very similar to the later TSR mindset, but with more bucks.
7) We'll do d20! Dancey is blessed for the OGL. Not to be outdone by Dancey's nefarious wizardry of D&D cause and effect, WOTC makes the new D&D an overnight success and before the BOOM goes BUST!!! sells to HASBRO. In between, the too many uncreative types, now lead down the path of uncreativity by hundreds of releases perfectly sculpted for their perfect game, are inundated with thousands of dollars of choices and less to do with them! Buy. Dispose, Buy. Dispose.
8) 4th Edition. Old School attrition. Does the band play on? One shall see. Looks like a lot of adventures to me.... hmm.
9) Now that the original vision has been reverse engineered, now that everyone knows what "IT" was all about, let us tune in for the next event, such as, how to reverse engineer what was going on before it all went bust, and furthermore, how can this all make sense to the people who are still drawing maps and designing their "stuff" from the old days? And what about those who actually itch to pick up a pen or pencil, and god forbid, draw or create something! Well, they are wearing head-sets now, so not all is lost...