You make many good points. I've found Steem to have a pretty lively community. And there is a range of content published through many apps such as DLike, which is a link sharing app.

I agree on the quality content snobbery. Mainstream adoption is definitely not in quality content. It's in mediocre content - by definition!

You're right about loss aversion but I honestly haven't found flagging a huge issue myself. There are some controversial figures who have been shadow banned or outright banned from elsewhere such as @tommyrobinson here. They seem to be exercising their freedom of speech just fine. Besides, Steem is not Steemit or any other particular front end. No matter how much SP you have, you cannot delete anyone else's content from the chain. Front ends other than Steemit do not let flags influence the visibility of content.

People are happy on Minds, not because they are not earning anything, but because they most likely don't even realize they could earn something for what they post online. The whole concept of users owning and governing the platform they use is so radical and novel that most people aren't even aware of how badly they're ripped off on traditional centralized platforms.

The economic model of Minds is something very different from that of Steem. Steem is no longer primarily a social media platform. It's a fast and free blockchain-based content delivery system. It's most high-traffic applications are actually games these days.

I agree on e-commerce. There was a startup called DStors here but it failed on its own accord.

Memos can be made private simply by adding the # sign in front of them. For example, '# This is a private memo' could only be read by its recipient and sender.