The multi-rotor kits that 3DR produced were kind of weak compared to what was in the market and while 3DR brought order to the APM universe it's an open source system that was already out there to be co-opted and branded by 3DR, no?
No, not really accurate to say APM was out there, and was co-opted and/or branded. The history of APM and 3DR are intertwined to such degree it would be almost impossible to separate them. In the early days, 3DR supported the APM developers with purpose-made hardware, without which the software never would have gotten to where it is now. Software needs hardware to run on, and vice-versa. And 3DR has supported APM developers more directly. Without APM developers, 3DR wouldn't exist. And without 3DR, APM wouldn't be where it is today. Also, in the early days Chris Anderson and Jordi Munoz were actually contributors to the codebase, meanwhile, APM developers helped develop 3DR hardware, some eventually becoming full time employees.
There are a number of other UAV projects around, which did not benefit from this symbiotic relationship. They are not as widely used and successful. Some of them have trouble gaining new users as they don't have a profitable hardware company capable of producing enough hardware to keep up with demand.
I just wanted to clear that up, as it sounds like you're saying that 3DR took control of APM. It's not really like that, it's a partnership.