From the article:
> It would be unfair not to mention that Sequel showed up already around the same time and till this day itβs being used way less than ActiveRecord despite being a superior solution.
Just because something was called "Session" (ala Hibernate) instead of "Unit of Work", people would claim it wasn't "pure".
The only real compromises for purity were for performance. You saw the same thing play out with ActiveRelation. Ruby is (or was at least) just too slow for complex patterns unless you wanted to pay a huge performance penalty. The kind of slow that materializing 10,000 models in an O/R Mapper would bring your app to it's knees and use hundreds if not gigabytes of RAM.
And since a large reason for writing DM in the first place was AR's miserable performance at the time, it needed to be fast.
Most of the community wasn't that interested in closing open issues. Not that I blame them. It's not fun. But I was burnt out.
During the end, ActiveRelation started development, making many of the same mistakes early DM did in the quest for purity. By that point I just wasn't feeling it anymore. I'd spent orders of magnitude more effort on writing an O/R Mapper than I'd ever hope to recover, and I felt like some of the ideas were fundamentally flawed. So I moved on.
If I were still doing Ruby, I'd be using Sequel though.
You certainly can use each individual part of Rails without having to bring in the rest of Rails. I bring in ActiveSupport all the time on non-Rails projects. For ORM I prefer Sequel, curious why solnik didn't mention Sequel, the creator of DataMapper even said that Sequel was everything he wanted DataMapper to be and I can't help but think that played a big role in the decision to not continue developing it.
You can use Sequel in Rails, I personally prefer ActiveRecord as I'm not aware of a Form Helper gem that works with Sequel, though to be honest I never really looked. Way more people use AR than Sequel, so Stack Overflow debugging goes much smoother.
I'm not saying he's wrong for leaving the Ruby / Rails ecosystem. I'm saying his stated reasons are inconsistent with his course of action. I'm fine with his real reasons, I just wish he wouldn't frame it as a slight to Rails.