Sure, but the communication is still encrypted.

Good point, but what's the point in encrypting data if it just goes straight onto the hands of an adversary?

Sure, other adversaries can't also steal a copy of the same data, but I'm not sure if that's really a concern if you've just handed your bank account login to gangsters. They can't steal your savings if someone else already stole them first, if you catch my drift. And if it's some other random login-password combos, you'll just end up with your password in two darkweb dumps rather than one.

I'm not saying that you're wrong, but it's a relatively minor distinction. Both self-encrypted https and plain http deserve big warnings for end-users.

I suppose it's all pointless anyway, now that I think about it. The NSA's BULLRUN can purportedly break TLS-based encryption. I'd wager that they backdoored themselves at the cert-isssuers, Clipper-chip style.

So I find it funny that when you access http site you don't get a warning about the site being unsafe...

What browser are you using? I use Firefox, Mullvad Browser, and occasionally Chromium (all on Linux), and they all complain about plain http sites (as far as I recall).