If I were going to play a game where 90% of worldbuilding was handled collaboratively with the players, I would rather do that in the context of a specific game, preferably with mechanics and guidance on how to handle that collaboration, particularly with regards to conflict between players on how the world should look. "Classic" RPGs handle this conflict with clearly defined purviews for the different participants. (As a player, I and I alone control my PC, and you, the DM, control the world and and its not my place to tell you how many bars there are in Baldur's Gate.)
I'm not 100% sure what you mean by "handling worldbuilding collaboratively with the players".
I don't know of any game in which the player is simply authorised to tell the GM how many bars there are in Baldur's Gate, but part of the context for this is a lack of context for the suggestion ie I'm not able to think of a context in which action declaration by a player for his/her PCs would entail determining how many bars there are in Baldur's Gate (eg if, in the game, there is a trivia contest on, it seems unlikely that the actual answer to the question would matter, and so it seems unlikely that anything would be at stake in the player rather than the GM deciding on what that number is.)
I do know, though, of a game where the player can delcare a Bars-wise check for his/her PC to find a particular bar, or to recall the famous bars of Baldur's Gate - if the check succeeds, the players declaration succeeds; if it fails, the GM is entitled to establish some fact about bars in Baldur's Gate that will thwart the player's intention in declaring that action. That game is Burning Wheel.
I also know of a game in which a player can declare a Streetwise check to find a speak-easy or an illegal casino, and if the check succeeds then the PC finds what s/he is looking for - that game is Classic Traveller (at least in its 1977 version).
And I also know of a game in which a player can spend a resource (fate point, from memory) to have his/her PC recall the existence and location of a friendly bar - that game is Mongoose OGL Conan.
Even AD&D has at least two contexts in which a player can, by engaging an approriate player-facing mechanic/system, bring about certain elements of the setting:
The first is the development of a stronghold: from Gygax's DMG (p 93):
Assume that the player in question decides that he will set up a stronghold about 100 miles from a border town, choosing an area of wooded hills as the general site. He then asks you if there is a place where he can build a small concentric castle on a high bluff overlooking a river. Unless this is totally foreign to the area, you inform him that he can do so.
Here we see the player enjoying authority to establish minor points of geographic detail, provided it is not "totally foreign" to the established fiction about the campaign world.
The second is a paladin class feature. From the DMG (p 18):
When the paladin reaches 4th or higher level, he or she will eventually call for a warhorse (as detailed in the PLAYERS HANDBOOK). It will magically appear, but not in actual physical form. The paladin will magically “see” his or her faithful destrier in whatever locale it is currently
in, and it is thereafter up to the paladin to journey to the place and gain the steed. As a rule of thumb, this journey will not be beyond 7 days ride, and gaining the mount will not be an impossible task. The creature might be wild and necessitate capturing, or it might be guarded by an evil fighter of the same level as the paladin, and the latter will then have to overcome the former in mortal combat in order to win the warhorse. In short, the gaining of the destrier is a task of some small difficulty which will take a number of days, possibly 2 or more weeks, and will certainly test the mettle of the paladin. Once captured or won, the warhorse knows its role and relationship to the paladin
Here we see that the player has the authority to require the GM to introduce certain elements into the gameworld (ie the existence of a magical steed, destined to be the faithful servant of the paladin who calls for it, in a circumstance that will impose some not-isurmountable challenge to the paladin in obtaining it).
The examples from Traveller and AD&D also show that the allocation of roles that you attribute to "classic" RPGs is not as straightforward as is sometimes suggested. I think it's true of classic dungeon-exploration D&D. But once you get to other aspects of D&D, like stronghold development and a paladin's warhorse, the picture changes. And Traveller makes it pretty clear, and not just in its rules for Streetwise skill, that the players are expected to contriburte to establishing elements and details of the setting (eg when a world is rolled, and its properties seem strange, the players as well as the referee are expected to help make sense of the overall picture - see Classic Traveller, Book 3).