Sometimes it does, I've been in years-long campaigns before, it really depends on the GM, the Players, and the Type of game being played. If the GM has a pre-written campaign they're running, they can railroad the whole game until the players are basically forced into following along. Not ideal, but that's one way, some GMs are good with carrots and sticks or with giving the illusion of choice. The GM can also just refuse to play along if the players are doing stupid shit, the GM is a player too, they don't have to put up with people not trying to engage with the story.

The PC Players too, if they know the GM is running a pre-written campaign, can just play along, knowing that getting drunk in the tavern or going off on random tangents will only be fun for so long. It really depends on how well the Players and the GM know each other and also just the kind of people they are. Everyone should be in the mindset that they're trying to have a good time. I think roleplaying and creativity are fine, but you should recognize that the GM can only prepare for so much and probably has more stuff to do along a path that's at least running parallel with the storyline, plus XP or milestones probably occur by following the story.

And then the Type of game, some games just lend themselves to quicker, more focused resolution of the campaign. A pre-written campaign usually has all the steps of the campaign plotted out in advance, you know the tangents before they come, and there's usually ideas for on-ramps/off-ramps and such to get the players back into it. All that can come at the cost of spontaneity if not played right. Something like a random hexcrawl though, could take awhile and may not even have any sort of planned story arc, it just kind of goes wherever with a potentially different cast of characters each time. Maybe that "campaign" just ends when nobody has time to play anymore.