I'm surprised we haven't heard more lawsuits about this in notoriously litigious America. I find it hard to believe that "we can ruin you at any time" is a sustainably fair contract term.
I've had surprisingly decent luck with bankruptcy attorneys being willing to do small favors like unfucking these types of disputes (or at least telling you the right incantation and process to do it yourself) for free.
(Maybe it has to do with being used to dealing with clients that literally have no money.)
That only covers the incentive for the lawyer for one isolated case. But since such a lawyer will probably take many such cases (and often against the same banks), we must examine the incentives of such a lawyer more closely. The incentive of such a lawyer is to keep taking such cases, which means it is actually in the lawyer’s interest to deliberately lose some amount of such cases, in order to keep it profitable for the bank to keep debanking customers, thereby ensuring that the lawyer has enough business.
That implies the lawyers act in cahoots to try to influence this much greater body of people/power, over and against their immediate interests. It also implies they're fully crooked. It seems like an extraordinary claim (well, the former).
Lawyers aren't limited to isolated cases. Class actions exist for this exact reason and regularly lead to hundred million dollar+ payouts from banks and other large defendants for harm done to large groups of people.
They will say you agreed to the terms they can close the account for whatever reason, and that receiving the balance within a week is quick enough. I doubt the courts would say otherwise. Lawyers probably won't take this case.
This is a situation where the Invisible Hand of libertarianism was supposed to manifest and gently nudge people to banks with more favorable terms in such numbers that no bank is able to do this and stay profitable.