It's not at all uncommon for monopolies to provide benefit to the public. They're uniquely capable of doing so, given their vast wealth and power. The problem is that they ALSO cause harm, and that benefit ends up not being worth the harm.

What harm has Big Tech caused? We don't have an Internet anymore thanks to them. Not a real Internet. Seven or eight major sites and a smattering of others you occasionally visit is not the Internet. The Internet is supposed to be a vast sea of individual sites, small communities and small businesses each discoverable, each doing their own thing. Instead we have a few walled gardens you barely even need two hands to count.