I do agree with the original contention that it's just a proxy for popularity. All of the things that you just mentioned may be factors. But at the end: these factors are probabilities that are mixed together in a nonmonotonic way somehow, and then multiplied by the total number of people out there doing stuff with the langauge. I would expect that that latter aspect is the dominant one in determining the ranking by language.
I would expect advanced people to ask just as many questions as beginners (they just do more advanced stuff, and ask questions relating to more advanced things pertaining to the langauge). Good documentation does not stop people from asking questions, as questions are frequently asked to which "RTFM" is the answer. Schools? Actually pupils asking "do my homework" questions is probably a driver in the opposite direction.
I can't disagree with you because that's an issue of semantics. I would define "popularity" as the number of people using the language, regardless of skill level.
By that definition, I'd guess that Python is near the top due to its recent dominance in data science, but Stack Overflow isn't proving or disproving the idea either way.
Using my definition (and likely yours), JavaScript is certainly the most popular. But it's hard to discount the many huge organizations using Java and C#. Their beginners might not be using Stack Overflow as heavily because they have in-house mentorship.
"most questioned" is some combination of:
- many beginners
- incomplete or outdated documentation
- not taught (or taught well) in schools
- SO users who don't search for old answers before posting again
See how none of those things, even mixed together, are a good proxy for popularity?
We don't know the mix of the above factors for Python, but without better analysis, the headline here is meaningless outside of its specific claim.