As a web designer, I was working on a Facebook competitor website that we called Mea Omnia in 2012 and we were trying to make it a one stop shop. Our project failed. Now, I like Steemit. And also, this Open Seed thing appears to be promising, like you said, as a cross platform. So, I do wish the best for this project. Speaking of Gab, I do use Dissenter which lets you comment on any web page on the Internet via the Dissenter add-on or tab inside the web browser.
RE: OpenLink: The Gateway to OpenSeed and Steem