I'm saying it's quite strongly recursive

I suppose 'quite' is a relative term. It's improvement with a bottleneck that resides firmly in the human brain.

and noting that recursion isn't magic fairy dust, the curve of capability limits rate of progress even when you do have recursive self-improvement.

Of course it does. Which is why it matters so much how steep the curve of recursion is compared to the curve of capability. It is trivial maths.