The thread title really says it all. But here's some context to explain why I'm asking that question.
In classic D&D, the dungeon was a type of puzzle. The players had to map it, by declaring moves (literally) for their PCs. The players, using their PCs as vehicles, had to learn what was in there: this was about inventory - having enough torches, 10' poles, etc - and about game moves too - searching for secret doors, checking ceilings and floors, and so on. And finally, the players had to try and loot it while either avoiding or defeating the monsters guarding the treasures and wandering around the place - this is what the combat mechanics were for.
The game is something of a cross between a wargame and a complex refereed maze. And *worldbuilding* is all about making the maze. I get that.
That is where I'm going to start but I'm going to say a few more things. Here are three types of "worldbuilding" (in quotations here because two of them will be cases of pre-built worlds):
Moldvay Basic
The creation of a dungeon (coming up with a setting, a theme, and then the map, the puzzles and stocking the whole with everything from treasures to denizens to fauna/furniture) is tightly integrated with the rules. You've got the movement rules that make specific assumptions about setting premise (it will be dank, dark, and require constant effort to orient and search) which interface with the Exploration phase which interfaces with the map and key (the layout and how its stocked) which interfaces with Wandering Monsters/light sources and other time sensitive resources, which interfaces with Reaction.
The whole of the game's mechanics is tightly (beautifully) integrated with the worldbuilding. Crane's Torchbearer is inspired by it (therefore shares much of the same procedurally and premise/theme-wise along with its Burning Wheel influence)
Blades in the Dark
This is veeeeeeeeeeeery mechanically weighty system and built world (though agile and extraordinarily user friendly at the same time). You've got a pre-built setting that hooks amazingly deeply into the game's premise (a gang of ruthless scoundrels at the bottom of the power ladder in a city akin to a post-apoc + supernaturally-charged England at the beginning of the 20th century, scratching and clawing against all odds to climb it) both mechanically and in terms of situation framing (conflict-charged off the charts...a powderkeg with a lit fuse). All of the game's (very many) mechanics for advancement (for both singular PCs and the Gang as an organism) and setbacks are amazingly integrated with each other, with the game's procedure setup (Free Play to develop the intel/plan for the next Score > Score > Downtime/Fallout) and amazingly integrated with the built world (our "worldbuilding" here if only any of us had the time or ability to develop such a setting and system machinery so wedded).
D&D 4e and Dogs in the Vineyard
You have a base setting/cosmology with a conflict-charged premise. 4e has Points of Light or good/civilization on the brink + the Dawn War and all of its fallout. For Dogs you have a supernaturally charged Wild West that never ways where God's Watchdogs mete out justice and take care of the Faith (therefore the faithful) against the malignance of sin and soul-corrupting influence. These hook directly into the conflicts inherent to each game's premise and individual PC build flags. For 4e you have Background/Race/Class/Paragon Path/Epic Destiny/Quests for 4e. For Dogs you have the general Background system which includes Traits ("I used to break horses with my pa" or "I can't see a damn thing without these spectacles on") and Relationships ("My older brother is my hero" or "I see foul sorcery, I kill the man wieldin' it") and the player-authored kicker for an Initiation conflict that will further shape the character. GM-side you've got the baked-in premise of a conflict-charged setting in both and the procedures for creating and mechanically resolving conflict-charged scenes and evolving the fiction in 4e the Town creation procedures (more abstract, but akin to Moldvay and Torchbearer dungeon creation), the conflict resolution mechanics, and the tight GMing instruction of Vincent Baker (say yes or roll the dice and escalate, escalate, escalate, etc) in Dogs.
Neverwinter and Dark Sun are pre-built settings for 4e that do a great job of doing the work that Duskvol does for Blades in the Dark and showing how all of this stuff should work in concert.
Where worldbuilding can (not does, but certainly is quite vulnerable to it) become degenerate is when (a) it isn't integrated in any functional/coherent way with the game system's machinery/procedures, or (b) there isn't a baked-in, clear, conflict-charged premise that is hooked directly into and hooks PC build flags, or (c) it is a "precious" thing for the GM who, because it is, refuses to "kill their darling" (or allow it to be killed - eg manifestly altered in a fundamental way) because their primary enjoyment is showing off the output of their blood/sweat/tears/talent. (C) also happens with metaplot.
Note that (c) is irrelevant when you have players who are actually looking for a passive, setting/metaplot-tourism experience (of which there are a great many). In that case, it is not only not degenerate...its a necessity. Problems arise when the players aren't looking for a passive, 3-course meal of setting/metaplot tourism but the GM's compromised because of their investment in their built world/metaplot (in themselves and their vision really).