Maybe I could understand why people spend time on ReactOS.
No one not (even that article) kids themselves that it is a usable desktop today.
But its goal is to be an open-source, drop-in replacement for Windows.
Whenever it leaves Alpha, maybe around 2040, I'm sure it will fulfill all those goals and really give people options.
I can understand why people would spend time on it. But they suffer from the same problems as the other three (the useless ones). it's a tiny target, few people care enough, so they will never get big enough to produce a working desktop.