There are some important aspects of voiceism that the author does not address. There is indeed an aspect of prejudice and stereotyping, but accents and dialects intrinsically hinder communication to someone who is unfamiliar with them.

We cannot expect everyone to be familiar with every accent and dialect, so we have General American and Received Pronunciation as standard accents (and Standard English), which helps communication especially with weak English speakers and ESL speakers. So for some examples mentioned

> while we’re at it: can’t we let Steven Colbert speak in his natural South Carolina accent, or Don Lemon in the strains of his native Baton Rouge? As with bias against visible ethnic features (skin colour, the epicanthic fold typical of Asian people’s upper eyelids), exposure is all.

from another perspective, using one's native accent on TV when they are perfectly capable of speaking in a more standard accent is arguably more supremacist than "antibigoted".

There is a subtle but very important (wrt what is ethical) distinction between prejudice against one's native accent and dialect, and deciding instead to speak, or require to speak in a standard accent and dialect: the latter can be due to prejudicial pressures, but also often for mere intelligibility and comprehension, and I'm not confident that the author notices and appreciates the distinction.