Idk, but I can guess. In windows terminal and shell are not so separate as in Unix. For example, is cmd.exe is a terminal or a shell? I believe it is both. Probably it is the same with powershell.
This is a mistake, but forgivable, as Windows executable launch behavior blurs this distinction.
Just like UNIX shells, cmd and PowerShell are ordinary console programs.
The Windows equivalent to xterm and friends — i.e., the mechanism responsible for displaying console I/O in a window — is a bit complicated, has changed over time, and only recently (Windows 10 1809 / Server 2019) adopted a UNIX-like pseudo tty / terminal emulator model.
For a good overview of Windows console architecture, past and present, see
