Ecosystems, man. Possibly way higher barriers to entry for new players than before.

Google partly defeated Microsoft's phone platform just by keeping their services away from it. It's difficult to imagine any less powerful player having any chance.

Think of modern consumer applications and how much they depend on technology from Google, Apple, Amazon or Microsoft.

They can at many points enforce incompatibility for business reasons. That should probably be disallowed (car makers couldn't really prevent after market companies from producing compatible parts).