This proposal just moves the threshold, while making it even harder for weak English speakers to consume media. To the extreme, sufficiently strong accents and dialects effectively are another language, and we acknowledge that learning another language requires effort and exposure: I think we agree that this is beyond the threshold.
> Standardising on one accent over others so that more people can understand the speaker is a bit of a self-fullfilling prophecy, that is. If everyone is constantly putting on a particular accent, how is anyone going to learn to understand all the others?
I don't think it's necessary, beneficial, or feasible for someone to understand all the accents and dialects of English and keep updated on their evolution. One should learn to understand accents and dialects at least to the extent of interest and also to the extent that it helps intelligibility with the people around you. (This rule, applied to media, favors media using GA and RP).
Of course, if more non-General American and RP accents were heard in the media more often, they would also be more easily intelligible by more people than they are now.
Standardising on one accent over others so that more people can understand the speaker is a bit of a self-fullfilling prophecy, that is. If everyone is constantly putting on a particular accent, how is anyone going to learn to understand all the others?