So many of these projects are "mature" which means for many of them there is a risk to accepting random pull requests. In the past a growing project tended to t

So many of these projects are "mature" which means for many of them there is a risk to accepting random pull requests. In the past a growing project tended to take them without to much worry under the assumption that if a patch broke something it would get fixed. Now there is a fear of the effort required to dig through the mountains of code to "support" someone who is screaming about the code breaking.