There always seems to be an incompatibility between the people who made it, the people who use it, and the people who want to contribute. The latter two often try, but the former isn't interested in the help or has a very specific vision for the project and doesn't allow any input that isn't in line with that even if it's not in conflict.

It's hard to fault anyone in that triad 100%. Open source has a way of becoming infrastructure. People come to depend on tools made by people without the resources, interest, or personality to run an infrastructure project, or who won't budge on their vision to allow contributions outside of it that might help get the project to a point where it can attract enough vision-aligned contributors.

Forking potentially shifts the problem to a new triad, so it's not an obvious solution in all cases.