RDP is pretty easy to explain: if you need a GUI, RDP is infinitely smoother than VNC or anything else the Linux ecosystem has to offer. I even use it on Linux for things like livestreaming (OBS running in a minimal GUI like openbox). The are many similar workloads that are less "servers" and more "cloud workstations" that use GUI apps.

As for Windows in general, 90% of the Windows servers I see fall into one of the 2 categories: 1) they run some Windows-only software or 2) the sysadmins at the company know Windows, so that's what they use. If your company relies on something from 1), you're very likely also going to fall into 2).

Specific example: a company wanted to allow any employee to log in from any computer and be ablr to get work done. A VM terminal server was too heavy for their network and server budget and they already had decently powerful PCs, so they went with AD and that roaming accouts thing. They had to hire a Windows server sysadmin to manage it.

When they decided they also needed a good NAS, web server and backup system, they already had a Windows sysadmin on staff and the licences+over-spec required to run in on Win were still cheaper than hiring another sysadmin.