That's besides the point, you don't own the server. You cannot expect the server to work forever, or demand a right to access it.

You do own the client though. In the example upstream, the failure to support macOS clients can't be blamed on Nvidia because they already wrote AArch64 UNIX support.

You cannot use a monopoly market share product like YouTube as a weapon against companies who compete with you in other areas.

This is as basic as antitrust law gets.

When you have a monopoly like YouTube, yes you can expect to have an access to the platform if it prevents competition. It's textbook antitrust laws.