Yes, it occurs because of divisions in the opinions of the population.
If everyone agrees on something, gridlock somehow doesn’t seem to happen. Gridlock only happens when a large group of people support something, and another large group of people don’t support it, and both groups are represented in the government.
And so Group A can’t enact their Agenda A, because Group B keeps stopping them. And Group B can’t bury Agenda A because Group A keeps bringing it up. It’s a disaster! If only there were some way for Group A to always win without those pesky Group B’s ruining things! Er, I mean, if only there were some way for Group B to always win!
We enact Issue A until Group A is so large and powerful that Group B no longer has the political will to keep opposing Issue A. We can’t finally stop Issue A until Group B is so large and powerful that Group A no longer has the political will to keep proposing Issue A.
Is the problem that rich and powerful people have disproportionate influence on how powerful Group A and/or Group B are? OK, but how do you change things such that powerful people no longer have disproportionate political power? You can have a political revolution and toss the old bosses out on the street or string them up from lampposts, but now you’ve got to deal with the new bosses, who might be just as bad or worse.
Or, like the example of gay marriage, convince the people who really matter that the issue is either important enough to support, or unimportant enough to oppose, and suddenly the issue gets resolved. Identifying the people who really matter is an important part of the trick, as is convincing them. Convincing a plurality of corporate types is one way of overriding the opinions of the powerless masses. But millions of unimportant people marching in the streets tends to get the attention of the corporate types.
If your complaint is that the 1% aren’t paying attention, then start working to get the 99% out into the streets to demand that the 1% start paying attention. But you might have noticed that the 99% aren’t in fact out on the streets demanding change. Maybe they should be, but they aren’t. And so start organizing. But what if you get the 99% out into the streets demanding change, but those idiots are demanding all the wrong things? You can inspire the people to demand change but you can’t control what they demand, if you could you’d be one of the 1% controlling the ignorant masses.