The more trust a class of thing requires to be viable, the more you'll expect a small number of extremely powerful entities in that class.

The asymmetry can be grokked by imagining two options for a calendar scheduling feature.

One from a startup you've never met before who you have to give sensitive data to.

And the other, a service that already has your calendar data.

Which one do you pick?

The latter, unless the former has an expected value an order of magnitude beyond the former.

Over time the one with the edge will grow more and more powerful (thus requiring more and more trust) until only they are left.