Some people? By internet standards, w3schools is ancient, and has been linked by many people over the years. Here[1], I present you their main page from close to 14 years ago. The copyright notice says 1999-2000, and I think I first visited it in 1999, but I could be mistaken. That's a long time for links to accrue.
Seems like a nice passive income project - man pages for HTML / CSS aimed at beginners but with advanced information too.
I'm surprised it hasn't already been done. Perhaps it has and I just don't know the URL.