Thanks, I was pretty satisfied with the reference myself;)
I think in theory anyone can make Steem-based applications, so anyone with the skill, time and motivation could make a copy of steemit and just not show posts tagged with dtube, dmania, steepshot... Or maybe there could just be a menu where you could choose which platforms to filter out. I would love to try something like this myself in the not so distant future, once I learn more about the STEEM infrastructure.