Why assume everyone knows an acronym instead of spending the extra 1000ms to type it out once for us?
Sorry, I assumed people here were familiar with accessibility tech. (If I recall correctly, the marketing material for Kindles used to use the term 'TTS', I don't think it's that obscure.)
Think of it as an accessibility issue. Full words are more accessible.
If TTS is fair game in the context of e-readers, ms is fair game... literally everywhere.