Because if a website doesn’t work in your browser, but it works in everyone else’s, no one will say “oh that’s website’s badly written”, instead they say “what a shitty browser”.
So you have a huge web standard you have to respect, and then all the websites with non standard code you have to make work anyway.
Ubuntu is deployed all over the place for data science.
I’m fairly sure this is because data scientists got used to running it on their personal machines and can’t be bothered to learn another distro.