If they could be required to craft single issue bills, this wouldn't be as big an issue. Instead we get the clusters of good and bad that inevitably die or sometimes worse, pass.

If everyone agreed on it, Congress would have no problem doing it (Congress itself, after all, is a subset of "everyone".)

That's still not true. As long as a group within "everyone" (or multiple groups) decide that their support is required to pass the bill, they can suddenly demand concessions and the bill now gets complicated with good and bad.

> As long as a group within "everyone" (or multiple groups) decide that their support is required to pass the bill, they can suddenly demand concessions

Well, yes, but then everyone doesn't really want it, do they? Someone wants something else, and wants that something else enough that it is worth jeopardizing the supposedly universal goal for it.

Yes they do want it.

If you've ever negotiated, I bet you've done the same thing of jeopardizing something you want in order to get something else you want. If you never do that, you'll make a lot of deals where you're riding the edge of just barely acceptable and the other person is taking advantage of you. But in this case, with a standalone law, doing it gets pretty rude and we'd be better off if nobody did it.

It’s possible for everyone to want something, while simultaneously being incapable of getting it done.

A highly disproportional subset of everyone, maybe. Though uncapping the house wouldn't fix the Senate (maybe adding some more states would)