I disagree with your assertion that this "is exactly why we have 3 branches".

The normal idea behind "checks-and-balances" is that if one branch exceeds their authority, the other two branches can serve as a check on abuse of that authority. The argument being made by GP, though, is pretty much the opposite: Congress isn't overstepping their authority, they're abdicating it. It's basically like they want to be 'checked' by the Supreme Court, because they don't want to have to take a clear stand in the first place.

I feel like that's implied by the "balance" part of "checks and balances."

It's also simply the fact that politics abhors a power vacuum. If one branch of government abdicates its power, that slack has to be taken up elsewhere.

I would have hoped it could be taken up by the people.

Many of "the people" have gotten lucky because SCOTUS went "their" way over the last few generations. Part of that lies with Executive choices for judges and some has been a wildcard (Kennedy, Roberts on ACA, Gorsuch for the last couple of weeks).

It could all spin based off of the next appointment.

But The Founders clearly thought Congress should be somewhere else than yelling from the sidelines.

The people have ceded their authority in this regard as well, through their own apathy and cynicism. Democracy requires an educated and engaged voting populace that actually believes effective government can exist and politicians should be qualified and held up to a standard.

I don’t have kids so I have no idea what is thought/taught anymore, but this is the sort of thing I was exposed to repeatedly starting in late grade school through early high school. I found government boring back then so I didn’t elect to take classes beyond the basic curriculum in that area.

Each branch needs to be moving for this to work - even the gutters on a bowling lane require someone to start the ball rolling.

Do undue the decades assault on the very idea that government can be good or efficient.