But couldn't you say the same about the non-celebrity content creators here though? I mean, monetary value or not, people publish largely for notoriety, if they didn't they'd just write the stuff down and hide it in a drawer somewhere.

The difference is that those authors try to show. The "effort" factor is huge. Followers know this. If they see a content creator that tries over a period of time and gets only some rewards while another earns thousands by just popping in the platform, then this creates the false impression about what the platform is all about.

It's the engaging kind of content creator-cum-interactors that you refer to here that's needed, in order for Steemit to thrive, and I don't necessarily think being a celebrity nor being only interested in the financial benefits of the activity precludes someone from filling that role.

Celebrities don't even bother to do that. They rather separate themselves from the crowd. This also has been demonstrated here from a few celebrities.

The popularity of Reddit's AMAs is one example that springs to mind - most everyone participating is shilling for something or another, but they pay for it with their time and their willingness to interact beyond a cursory level.

Exactly.