Earlier quoted context omitted.
How exactly do you propose to split up Twitter? Split the userbase into 100 groups? Who goes in which group? And what happens when people want to switch groups... ultimately coalescing in a single node? Because, you know, network effects. I don't like Twitter either, so I don't use it. It's a really effective solution!
There's other ways to deal with anti-trust besides breaking the companies apart. Data portability, interoperability, ownership of your own social graph. If these platforms were forced to act more like email, where leaving google for microsoft doesnt mean i can no longer contact my friends, the network effects that give them monopoly-like power diminish. Imagine how ridiculous email would feel if you need a gmail acco…
Maybe this is the problem you’re hinting at, but I expect it would be very rare for me to ever run into someone I couldn’t email because they’re not using Gmail (especially if we include G Suite).