If someothing can't be seen as worthwhile by both sides, without payoffs, there's probably a strong argument for not doing it. Gridlock is generally a good thing at the Federal level.

What happens, then, when one "side" takes it as an article of faith that any plan proposed by the other side needs to be rejected out of hand? That's the circumstance we're in right now, and have been since 2008 at least.

To wit, Merrick Garland would like a word.

This is fine as a theoretical construct, but the reality is that a lot of the best features of American government were the result of quid pro quo deal-making. A huge example is the entire Bill of Rights, which was the price of creating a stronger central government. And the movie "Lincoln" illustrates (with only a little exaggeration) the deal-making that went into passing the 13th Amendment.

As an aside, I happen to think that there is an important difference between "bipartisan" and "deal-making," and the latter is really where it's at in governance. Earmarks are tools for deal-making.

Framing things as "both sides" inappropriately elevates the 2 major political parties as a central feature of our system of government. They're not; in fact the largest political affiliation in the U.S. today is "indepdendent"!

And on any serious legislation, there are typically more than two "sides" with an interest in a particular outcome. That's why making deals is so important.

Why do these discussions always assume rational or good faith actors, when that so obviously isn't the case?

No, just asking why it would be good. The claim was that it's so good that it's worth increased corruption.