"This is the biggest point, imo. We don't all have to like the same things, we don't have to all use the same tools, we don't have to belong to the same communities. There's room on the web for all of us."

Exactly right.

Tech companies that rely directly or indirectly on the survival and expansion of web advertising, i.e., most of them, prefer a world where web users do not think independently.

It is easier to advertise on (and manipulate) a web where every participant likes the same things, uses the same tools, and belongs to the same communities.