Maintainers of open source projects should be mentoring folks to become their replacements. Not just thinking this is about controlling their project.
I have learned this the hard way for gcc.
You can't just think it is your way or the highway. Also gsoc is NOT a replacement for mentoring inside the project. It should supplement the mentoring that is done, just like an internship.

Also this is not unique to gcc, it is many open source projects.
And then there is the gaming of github stats, the one or two commits in llvm and leave issue. Those are used to gain stats for a job.
Seriously open source is broken because of the gaming of the system.

Even inside companies where you have the person with the most open source commits. Or the person who opened the most issue. Or the person who reviewed the most. (What is funny is that i am that person but I am not trying to play the game of counting, I am just trying to push gcc forward).
At the same time I am mentoring folks both inside and outside of qualcomm on both gcc (and even to a less sense llvm) and performance analysis.
But going back to my original point is mentoring and maintainship overlaps. It is not one or the other but rather both in the same role.

By the time you step down you should have at least mentored a few to be able to take you from you. If you have not you partially failed a as a maintainer as the project will no longer can be maintained in the future.