The point being that I would expect stub article
creation to be pretty high
in new Wikipedias, and to tail off as the Wikipedia in question comes to be
seen as more authoritative.
That's a very valid point. That would contribute to an upward trend of
stub ratios with increasing edits, which is exactly what I see for
Wikipedias with less than 20,000 edits, but after that it levels out,
and becomes much less variable. I can't think why.