I'm well aware, and this does not rebut any of my points.

> I, for one, tend to find most non-native English speakers vastly easier to understand than many native speakers.

That "many" native speakers in a language of hundreds of millions of speakers are hard to understand does not challenge the claim that a non-native accent brought closer to any native accent, much less the mean native accent, will for the large majority if listeners be easier rather than harder to understand.