This is as much linguistic tomfoolery for humans as it is a con for computers.
I dont know the history, but the most likely case is some microsoft engineer implemented the “print as pdf” option to get around an adobe restriction in the far past, and now we have this weird convention where you can “print” to only 1 filetype to “save” it.
Thats not 100% correct. This didnt use to be an option, nor is pdf the default printing “format” used by printers. Thats more PCL.
“Print to pdf” was added to Windows at some point after PDF became a common file format.