I think it has a lot to do with whether you're primarily aiming for new functionality or for reliability. Clojure, GitHub, AWS, etc. are primarily used because

I think it has a lot to do with whether you're primarily aiming for new functionality or for reliability. Clojure, GitHub, AWS, etc. are primarily used because of their extra functionality, and downtime/failure is often inconvenient but not disastrous. Compare this to a database-reliability is tantamount. If there's a weird bug you need to ensure you have amazing support, you have access to dig into the internals and solve the problem yourself, or both. Datomic comes across as prioritizing functionality over support, e.g. they're closed Source and don't (yet?) have the reputation for Enterprise class support businesses usually look for with closed source DBs. That doesn't mean they'll fail, but I'm curious to see who Datomic's customers will be.