CapnZapp said:
It died when WotC decided to not rock the boat afraid that any new ideas would jinx the edition and stop the profits rolling in.
They avoid doing anything that could be interpreted as "new edition" like the plague.
It's there in the class design and optional rules in the DMG.
I think the fanatics took things a bit to literally. They said fans of 1E to 4E could play together not that it would be 1E to 4E.
What we were told and-or led to believe in the pre-playtest and early-playtest days were three things:
1. 5e would be 'modular', the intent being to limit or even eliminate knock-on effects to other modules when making changes to one
2. 5e would be designed with kitbashers in mind, such that a DM could - with more or less effort - massage the game into what she actually wanted to run
3. With enough kitbashing 5e could be largely made to play like any previous edition (the implication being that the 5e design would be robust enough and flexible enough to handle this)
Well, other than some options in the DMG 1 seems to have largely disappeared along the way. 2 may or may not ever have truly been the case despite what was said at the time; and 3 - while still true - would now take huge gobs more work than originally - 'promised' is too strong a word to put here, and 'implied' is too weak - due to the absence of 1 and 2.
The other thing they never gave us (in fairness they never said they would, but...) right from the start are conversion guides to-from each previous edition - how do you port a 1e Illusionist or a 4e Warlord into the 5e framework and make it work without losing the uniqueness of the class; or how does 0-1-2e style level loss work in the 5e milieu; or ... (I could go on for pages here). A 16 or 24 or 32-page softcover adventure-module-sized conversion guide for each previous edition (so 5 of these, 1 each for 0e/BECMI and 1-2-3-4e) is all it would have taken...and it's work that was probably 90% done anyway during the design process - all they'd have to have done would be type it up and lay it out.
The only guides we have to go on, and these were all released well after the fact, are the updated-to-5e re-releases of some classic adventure modules from 0e, 1e and 3e.