Because it is cool to hate on React on hn. Write something in Rust and watch everyone swoon, but mention anything that uses React and the comments will be filled with people hating all over it. As is the way on hn.

You're right about the disproportionate hate for React, but your information about Rust is out of date. These days it's 50-50 whether you'll get a lot of love or hate for a Rust project, and several of the top-upvoted Rust posts of the past year are disenchanted ones.