Maybe it was too early back then to see the value in it, but does anyone remember App.net? Dalton Caldwell (now working at YCombinator) had a plan to build a backbone for developers to build on top off without fear of APIs being taken away from them[0]. The idea came about from this exact topic (Twitter becoming more and more hostile to developers)[1].
I remember App.net with fondness. I was a paying customer and the community was awesome, pretty much entirely troll-free techie types, and I never felt awkward just jumping into a random thread or conversation.
First was the great apps, and the features that continued to roll out for users. Unfortunately it was under appreciated.
App.net proved that locking down the API wasn't Twitter's problem. Once people got over the initial phase of trying out every App.net app they stopped using it. It was the thing that brought them there, but it wasn't enough to keep them using it, regularly.
"The bad news is that the renewal rate was not high enough for us to have sufficient budget for full-time employees. After carefully considering a few different options, we are making the difficult decision to no longer employ any salaried employees, including founders."
http://blog.app.net/
So effectively development stopped in 2014 and it's on maintenance mode since then.
First was the great apps, and the features that continued to roll out for users. Unfortunately it was under appreciated.