Well, based on our prior conversations I suspect you know far more about soil science than I do, I only know the basics necessary for arboriculture.

So what you wrote is of course accurate but I understand both to be at play here—leaves break down into humus that chelates minerals and supports fungi that can hold onto nutrients and keep them from leaching away in rain. Leaves also provide a physical barrier that protects soil from physical erosion. But let me know if I got anything wrong.

My overall point was mainly just that you don’t need to replace leaves with fertilizer if you are removing them, but it’s still a good idea to leave them in place for other reasons.