Making legit posts is already a nontrivial amount of work, and you'd have to be doing that on top of actual dev work, and then trusting that enough "curators" would vote for you to get rewards.

Time spent on posting is definitely a real concern. Many of my posts take 3-4 hours. We can't expect that with any kind of frequency, and that work takes away from productivity. I think curation policies would have to be developed that focused on the deliverable, and not the post quality. Posts would need to be accurate and the contributions they describe would need to be relevant. But, we'd definitely need a moderation/curation team that's able to separate flash from substance.

For myself, I would have a hard time shaking the expectation that it would be another round of "Lucy convinces Charlie Brown to try to kick the football".

It depends on rules and moderation. It's sort of hard to game a post when your only options are describing work you're going to do, providing progress updates, and demonstrating the completed deliverable. I guess the fakers wouldn't last very long when they have to put-up or shut-up in two weeks time.

From my POV I never got any kind of reliable support for my forays into doing dev work related to the chain.

This is why I focused on 2-week (or less) deliverables. If we have commitment from moderators and dedicated voting power, I can imagine a different dynamic at that scale than with people trying to do larger initiatives. The tasks could be as simple as updating the description in outdated documentation for one of the API calls. But, again, it depends on a moderation team that's consistent and actually evaluating the relevance of the deliverable.

I'm skeptical anything like this would make sense to people that aren't already involved in the community. I doubt that "sustained PR" can magically attract a bunch of new people.

I think it could, if done by someone with relevant knowledge and skills, but not if we just depend on a bunch of people to put hashtags in their X posts.