Google, Facebook and Twitter can only block you from Google, Facebook and Twitter respectively. ISPs can, and do, refuse service to some people. In some areas that means effectively being banned from the entire internet.

Admittedly bans/refusals from IPSs are orders of magnitude more rare, but I find it disturbing that there there are no regulations or oversight to an ISP refusing or terminating service, when access to the internet is so fundamental to modern life, and to many people's livelihoods.

I can't do my job without high-speed internet access, but I either don't use, or can easily replace Google, Facebook, Twitter, etc.

But they can “ban” parts of the internet. Verizon for example aha blocked its consumers form accessing Mangadex.