It operates in a successful niche. And it also is home to many far-right actors who hate Jews and minorities. Yet the claim is that breaking up the tech companies would help stop hate.
Tim Berners Lee has no salient point here whatsoever, and I don't think anyone would care about what he's saying if he wasn't who he is.
Not to mention he's calling for government regulation of tech companies at least partially to cut down on hateful speech (which is very much against the right to free speech).