If you don't like the question I'm answering, complain to Komponisto, not me.
I wasn't complaining to anyone. And I don't dislike the question. I was just adding some relevant information. Anyway, I did reply directly to komponisto as well. See the end of my long comment above.
But what would you count as a conceptual problem?
If we did not have independent evidence that QFT breaks down at the Planck scale (since gravity is not renormalizable), I might have considered the Landau pole a conceptual problem for QFT. But since it is only a problem in a domain where we already know QFT doesn't work, I don't see it that way.
I don't think that's the normal use of "conceptual problem."
If physicists believe, as their verbiage seems to indicate, that QED is a real theory that is an approximation to reality, and they compute approximations to the numbers in QED, while QED is actually inconsistent, I would say that is an error and a paradigmatic example of a conceptual error.
What does it mean to interpret an inconsistent theory?
From the last thread:
Meta: