Adding to that, I’m not confusing prevalence with clarity. The standard American accent is clearer and easier to understand than most other variants, including American subcultural accents like the Boston, Texan, or Southern accents.
>, I’m not confusing prevalence with clarity
...but you do that right here:
>American media (movies, news, etc.) is universal. People all around the world watch American shows and movies and are accustomed to the accent.
So it is prevalence and not clarity.
It is widespread common knowledge that the American accent is the easiest to understand. If you don’t agree with this, I’m sorry but you are not speaking from experience.
And yes, I have considerable experience of speaking English abroad, and whether I think the listener will understand me better if I exaggerate my British diction, adopt more General American-sounding syllables, pick up quirks of pronunciation and phrasing used in the local ESL lingua franca or pronounce a particular problem word as it is written is entirely situational, and generally based on what the person I'm speaking to is most exposed to.
I didn't know that this was established. I'd be curious to see a source for this — has it been studied?