[MereInterest]

Maybe this is just because I learned to touch-type rather early, but (1) typing "accessibility" is far faster than typing "a11y", because it doesn't require reaching as far from the home row and (2) it is rare that the limiting factor is the speed at which keys can be pressed, rather than the speed at which correct and accurate words can be chosen.

Text is meant to be read, and not just written. I'll agree that there are chunking benefits in acronyms and abbreviations when working in a shared context, but outside of those shared contexts, the abbreviations severely impede communication.