Within the fonts that aren't monospace, some fonts have less variation in glyph width than others. It's a spectrum. You can choose a font that is mostly monospace, but not completely, to confer benefits for readability.
If all you're saying is that you personally don't care to make a finer distinction than monospace/proportional, that's fine, but it's probably not worth commenting on either.
There is nothing that says monospaced fonts are more readable. In fact, they’re probably not since you can’t give neither whitespace nor character components like the ascenders/descenders/bowls/stem/etc the space they need to shine relative to each other.
Monospace has one and only one redeeming quality that makes it worth using over proportional fonts: it lines up.
Yes, I read the article to the end. No, I don’t get it. Either they line up or they don’t. Either it’s monospace or it’s not.