These junior developers also have a tendency to make improvements to the system by implementing brand-new features instead of improving old ones. Look at recent Microsoft releases: we don't fix old features, but accrete new ones. New features help much more at review time than improvements to old ones.

(That's literally the explanation for PowerShell. Many of us wanted to improve cmd.exe, but couldn't.)

[0] https://blog.zorinaq.com/i-contribute-to-the-windows-kernel-...

(I'd heard the story in person from Snover years before that, so it definitely wasn't just sour grapes from somebody about to leave the company.)

I can totally believe that MS had a culture where making improvements to cmd.exe was impossible to justify, but that doesn't actually mean that a greenfield project in the same space would be considered promo-worthy either. It seems more likely that everything in that space was viewed as career suicide and you needed to be working on Internet stuff, just like at today's bigco anything except AI will have the same problem.