Running on multiple blockchains is particularly interesting. I can imagine that in the future projects and applications will need to be multi-blockchain, like regular apps today are multi-platform, so they can run on Android, Windows, Linux, IOS. If you develop a new product, you don't really want to restrict your customer base to a single blockchain users, you may want to have your product running on all the main chains. Or I could be saying a complete horsshit right now :)
That's too much for me today..But does it really restrict users that Steemit is running on Steem blockchain?
Steemit - Steem - nearly one to one match. I was thinking more about apps running on a shared blockchains. Like for example many apps currently running on the Ethereum blockchain and probably many more in the future running on EOS, NEO, Cardano...
Now I could imagine a next generation Steemit / Facebook accepting/emitting tokens on various blockchains, based on user's preference. Such new platform could bring many different blockchain
users together. If I'm correct then Cardano is working on some kind of eco system enabling pear to pear exchanges of tokens between blockchains.