Thank you for taking the time to explain that, @lukestokes. I'm coming from a background of having used (as an end-user only) decentralised social networks like Diaspora* and GNUSocial/StatusNet (and now Mastodon), so I compare it to one of the "pods" going down, but not taking the entire network down with it.
But it seems that what you're saying here is that if all pods were running the same software, and there was a bug in that underlying software, then the whole lot could possibly fail, especially on a sync event, am I right? I guess the crypto side of things here (which neither D* nor GNUSocial etc have to worry about) means that all nodes in the Witness network for SteemIt must be running exactly the same software, and exactly the same version, huh?
Yep, that's essentially it.
Ideally we're all following the same protocol, but there could be multiple implementations of it in multiple programming languages. We're no where close that yet at this point though.