FIrstly the "Monopoly" model isn't the best comparison. Monopoly gets played didfferently from one house to another and except for ME, nobody I know has ever actually read the Monopoly rules - they just assume that they know how to play it. For the most part they're right, but as has been pointed out there are any number of house rules and overlooked details from the ACTUAL rules that can significantly change the game. The rules themselves now include a number of house rules as options. Furthermore Monopoly as a brand name has been given to any number of other games that are not even necessarily closely related to the original. Different versions of the original have also been devised to attempt to deal with its inadequacies as a not-really-well-designed game, since so much of the game relies upon random dice results (who lands where and when) rather than player strategy or tactics.
Even if you were to now create the "single, definitive version" of D&D you'd still have the problem of all those other editions still floating around out there. You would have to create this theoretical edition and then ensure that nobody plays any other version for the better part of a generation before you can be sure that everyone who has EVER played will be versed in the same ruleset as those who start playing this afternoon. Note that this means NOT just that everyone only sees one set of books but that nobody ever devises or uses house rules ever again. Unrealistic enough? Wait! There's more!
This theoretical ultimate version has to be one that everyone DOES want to play to the exclusion of all others... forever. We have die-hard fans of EVERY edition and the differences and preferences have been "discussed" at various temperatures for decades. You really think you can make everybody happy? That ANYONE will ever make everybody happy? Good luck with that.
I understand the sentiment, I really do. But yes you're dreaming to think it's even remotely possible, much less practical. The game has always been evolving even as every version has been put to print. It has never stopped changing and never will. And it isn't all just because we have different versions of the rules but because we all want different things OUT OF the rules. Some want gamist rules, some want simulationist rules, some want a bit of both. Some want simple rules. Some want to drown in options. Some want DM's to be firmly in control - some want players to be able to override the DM. Some just want to roll dice and kill things. Others want to wallow in thespianism. And they can want all of these in the span of a single nights gaming much less over decades of gaming experiences.
I'm edition-fatigued. We all play the same game with about a 1% difference between the editions/spinoffs/clones in what the actual game is. Those small variations on what is essentially the same thing create huge logistical barriers to actually playing the damn game.
Nope. I don't think you can have it both ways. These are either insignificant differences (both in amount of change and degree) or they are huge logistical barriers. And since it's YOU who's edition fatigued this can only come into play when YOU are changing editions - otherwise it's just a matter of teaching your chosen edition or making older players reaquainted with the game
as you play it that has you fatigued.
If you meet Jim and invite him into your 3.5 game then yes, Jim may have to go buy a 3.5 PH. He shouldn't need anything else but dice to get started playing (and more importantly shouldn't want anything else until he's got his feet under him as regards those rules). This assumes Jim is unfamiliar with 3.5 and that Jim has no access to a computer to look at the SRD online anywhere.
If you meet Jerry and invite him to play your 2E or 1E game then if Jerry is unfamiliar with those rules he may need to buy a $5 PH off of Ebay or Amazon to get started - but you should be able to provide him with any other materials he might need at the start since you're running the game. Even if Jerry has played 1E and only 1E his entire life he is still likely to need YOU to explain how YOU run your game, what classes and races are available, the basic information about your game setting, house rules, alternate surprise and initiative rules, and on and on.
If you meet John and invite him to play in your 4E game but John hasn't played D&D since 1977 using the little brown books of OD&D is it not EXPECTED that either he would invest $40 in a new PH in order to participate or that you or someone else at the table would be able to provide him with a spare? Why would you invite him if you're going to turn him away if he turns out not to have the exact same gaming knowledge and understanding (much less materials) as you do? Of course you wouldn't.
This is all something that I think you just have to accept as part of the hobby in general - not everyone has the same knowledge, the same resources, the same experiences in gaming in general much less playing D&D in particular. You know, I think it may actually be GOOD for D&D and rpg's in general that we have so many different versions and so much inconsistency between them. This is not a problem - THIS
IS D&D! </sparta>
Now, if you're telling me that the problem is that the older versions are not IN PRINT sign me up to that petition.