Windows 7 general support ended in January, so anything involving it is on Microsoft's "we'd rather not" list.

But many companies will be on it for a lot longer and this is version 3 of WinUI. The question is "what tech stack can we use to target all current versions of windows and isn't being deprecated anytime soon?", as windows 7 dies out this may become the answer but for the past several years and probably the next few Win32 is the only possibility.