As you say, I came to Steemit on a recommendation from an acquaintance in another network, although in my case the reason I used my social networks was to share content for my classes.
When I arrived here I thought of using the site more as a personal blog and sharing different things that would catch my attention and like me. Something that was wrong was to withdraw and change in other cryptocurrencies at the beginning, then I understood a little better that this project needs the support of its users and also that it was fun to have more resources available to comment and create new posts too.
You are right that I have not seen much publicity of this network on YouTube, nor on instagram, although I believe that I have seen some twitter accounts that promote the benefits of STEEM. I think that your proposal to develop a campaign to disseminate and publicize the network is good, maybe it could be a bit different, so it could be good if a group were formed or coordinated to make your idea come true.
RE: Cold Calling the Steem Blockchain to YouTubers!