They emulate ANSI control sequences originally intended for dumb terminals and the teletype bell.

Which were never a thing in MS-DOS, Windows, OS/2, Amiga, Atari,...

That's not true. MS-DOS and Amiga supported ANSI escape sequences, I remember that very clearly. Through MS-DOS, Windows and OS/2 would have had some form of support available. No clue about the ST

Yeah, but not as dumb terminals, hence no emulation.

There were products like Concurrent DOS, Windows Terminal Server…

None of them had anything to do with UNIX terminals.

Ironically you even list one that is a RDP server, completly unrelated to CLI.

Random Google search without diving into details?

I worked with Concurrent DOS about 25 years ago.

I had heard of Windows Terminal server but I’ve barely touched a Windows computer in 20+ years.

Since Windows Terminal application doesn't care about Concurrent DOS ever existing, and Windows Terminal Server is actually the Windows version of X Windows based on DirectX and grown out of Citrix networking protocol, they don't apply here.

Does Windows Terminal replace HyperTerminal too? Hadn't thought about that one in a while.

That thing died long ago and is completely unrelated.

Wikipedia says Windows 10.. but that was the previous terminal emulator in Windows, right? There was MS-DOS prompt and then cmd in NT (4?) and HyperTerminal..

ansi.sys would suggest otherwise.