DOS stuff is still in there. You cannot name a file "con" among a few other reserved names because those were reserved for outputs (that one was the "console") back in DOS. And in fact, I believe some of those came from CP/M at that.
Just one reason Windows can be a bit flaky - and although not everything from past versions works, a surprising amount does.
So while Microsoft probably sucks for many reasons, they do a not totally bad job in some ways arguably. :)