You nailed it. HABTM just never worked, and there was little interest in making it work. Since I handed out commit-access like candy, the majority of contributions were to endlessly refactor. Or do things like letting you treat a CSV file as a database. And HABTM still didn't work.

I didn't know how to put the genie back in the bottle. I didn't have the same problems that prompted me to create DM in the first place anymore (and by that point, I wasn't sure that porting a large Java Pattern to Ruby was even a good idea considering what I'd learned in the process about method dispatch performance in Ruby) and I was burned out on maintenance. So I handed over the keys and the rest is history.

I messed up. :-)

Today I'm happily writing apps with akka-http and think O/R Mappers are a fundamentally flawed idea. It's like trying to build a truck to move a few yards of dirt 100 feet. It'll never pay off. And I think even "users" would probably find that the hours they put into learning and using the tool will never get ahead of the performance, simplicity and linear scaling of effort they'd have had with a simpler solution.

So these days I'm much more likely to write this in Scala:

  val limit = 10.0

  sql"SELECT name FROM coffees WHERE price < $limit".as[String]

Than anything else. You will never find an O/RM that's faster, simpler or easier to write and maintain than that.

Plus Contextual Validations in the O/RM is just a bad idea. Even if they do appear in the PoEAA. First-class-Form objects and deserialization/validation at the app boundaries may not be a new idea, but it's the right one. (IMO)