Open source culture has changed so much over the past couple of decades that it seems totally reasonable now for up-and-coming maintainers to question the whole thing.

Scale has changed everything. There are orders of magnitudes more users than contributors compared to some of the early OSS and the balance between grateful and entitled end-users has skewed expectations much more towards maintainers as a support role with similar responsibilities to a product engineer in the commercial world. Why would you want to enter into that social contract now? Why would you want to risk your library taking off and the associated costs that would bring (as well as benefits)?

An alternative evolutionary pathway for OSS is for developers and communities to self-host their own git projects. Projects get to define their own ethos and workflow. Discovery remains high-friction which prevents the commodification of maintainer effort. The bar for writing custom tools to support things like this got a whole lot lower so it might start to make sense more than it did in the past (there are both push and pull forces at work here). It might even make OSS fun again.