Because the internet is purely an information medium, so "borders" on the internet can be nothing other than censorship. Censorship is a human rights violation and is disproportionately useful to oppressive regimes.
Why should it not? What's the point of having an effectively open information network if you're going to just let each nation state arbitrarily censor/manipulate it as they see fit for their own peasants?
You'd agree with say, <insert country> mass blocking sites for their people just because the sites say something about democracy?