Thinking about platforms and critical mass...
It feels like all major platforms gained traction because they offered some new and desirable feature. Tumblr/Twitter had takes on microblogging, Facebook: social graph, Vine: micro-videos, for example.
So when a platform alternative pops up that does basically all the same things that the original did but it's open-source/decentralized/whatever, it's no wonder it doesn't catch on. Open-source isn't a feature to most.
It is for some (like a lot of us here, me included) but it makes me think that to gain critical mass on a platform, it has to have something *new* that people recognize as a feature. Something that will improve their lives there and then. Once it has users it could potentially expand out and supplant the previous dominant platform.
This Mastodon instance is for people interested in technology. Discussions aren't limited to technology, because tech folks shouldn't be limited to technology either!