Right now, we depend on different behavior of the quick pick when using a screen reader so that the quick pick is accessible. However, the change we made last iteration to make it accessible, also made it less usable.

Lots of good info in this thread:
#166920 (comment)

The overarching problem is that a quick pick cannot have a placeholder and set active items at the same time because the placeholder must be read out by a screenreader to be accessible.

We should try out using aria-live instead of aria-activedecendant to make this work.