A beast if a Windows PC to do what? Run Trams, Excel, Outlook, and a browser all at the same time? We could do that just fine in 2010…
The idea that any hardware performance increase will be eaten up by terrible software is an evergreen. A computer that could serve as the single server for a medium size enterprise 20 years ago, is no longer able to serve as a desktop for a receptionist. I'm not even sure we're talking diminishing returns anymore, we're probably past the point of maximum yield and into the negative returns at this point.