alt Hacker News> the population of people merely using Emacs and lightly hacking their own setup
This is a good thing. Custom environments should be either minimal or upstream. Anybody should be able to sit down next to you and help you hack out a change. The more unusual/custom your environment is the less productive that is, and this more than balances out any possible gain you can make from custom setups. (don't forget to account for your cost to learn elisp and then make the changes!)
Somebody needs to make the correct setups. However most of us have better things to do.
I'm not advocating for making all (or even most) users spend so much time on internals that they don't get productivity gains. Rather, I'm concerned about maintaining, ensuring generational turnover, and healthily boosting the elite that the product depends on. It is no secret that a number of Emacs ecosystem core devs are middle-aged, and so the project is a few heart attacks or whatever away from losing the experience and competence that has sustained it so well.