I'm not sure it's free speech exactly, but the ability to hang put with like minded people exclusively. The internet makes that fairly easy. You just ban everyone who disagrees from your little forum, or drive them off.

I don't see any clear fix though. Even the big sites like Facebook and Reddit have that going on.

Of course, I admit this went on before with things like religious groups that isolated people to convert them to the cult, but it's far easier to generate the effect now.