Ask HN: Why is nobody using gemstone/s?

This is something I was always wondering: Essentially, gemstone/s is an OO environment with transactional persistent "heap". So all what you need is to put somewhere reference to a graph of objects and it will write all of them to disk automatically (and there is no ORM problem). It's not limited (or doesn't have to be) to smalltalk either - there was a project called Maglev which would allow you to write code in ruby. Is there anybody who has/had experience with gemstone? What were the pain points or is it simply that RDMBS are easier to optimize for speed or is it because of the tooling? Or because of SQL being universal query language? Or what? I understand this is very subjective but I'm still eager to hear anything.