It's the same thing in textbooks. Why are all the textbooks liberal? Well, yes most of the profs who write them are libs, but even if you get a conservative textbook, the editors and copy editors and most of the publishers are libs. So it's VERY difficult to get a conservative book through the process.
It is the same thing everywhere you look. Liberals have built their careers on self-referencing “critical” groups.
Look simply at book reviews. The winning writers are liberals, reviewed by liberals who praise their liberal writings which then are considered “Best Sellers” and bought by libraries and schools and made assigned reading for students.
The entire thing is a scam built on a house of cards.
This is why the internet must stay free!