If that was the only reason, they would proactively cooperate with alternative app-stores like F-Droid to allow them to provide a lesser friction flow for open

If that was the only reason, they would proactively cooperate with alternative app-stores like F-Droid to allow them to provide a lesser friction flow for open source releases. My question would be why I they see themselves as the only possible trust anchor here. A high friction method to install a different app store, once, IMHO would be OK.