I wouldn't say the minor third is a "passing tone" at all, it's the defining note of the minor scale. Listen to e.g. "Mannish Boy"--the minor third is absolutely essential to that riff.
Agree that of course there are blues songs with definitely minor harmony, but I still think the really distinctive and innovative characteristic of blues is "minor melody over major harmony"--the minor pentatonic scale was already ubiquitous in African-American music in e.g. spirituals. That's just incredibly weird and I can't imagine how it must have sounded to white audiences hearing it for the first time.
I think you’re misunderstanding the context I was replying to.
Of course a minor third is important to a minor scale. But if the underlying harmony happens to be a major chord, then the minor third is dissonant relative to the harmony.
I referred to this dissonance as a passing tone because you said “ There’s no way that combination can possibly work—but it does!”.
Agree that of course there are blues songs with definitely minor harmony, but I still think the really distinctive and innovative characteristic of blues is "minor melody over major harmony"--the minor pentatonic scale was already ubiquitous in African-American music in e.g. spirituals. That's just incredibly weird and I can't imagine how it must have sounded to white audiences hearing it for the first time.