If you cared about "cancel culture" and platforms having too much leverage, you'd be a lot more concerned about this duopoly than whether Twitter lets Nazis speak.
That's just objectively false we have a long history of forcing companies to take customers from Utilities, Americans with Disabilities Act, anti trust laws, forcing companies to license technology, and a whole bunch of other ones when needed; This is no different.
We are talking about it because we find the current state with Visa and MasterCard as unacceptable.