The alternative here is pretty obvious - a text box.

'Don't be a jerk' is the more important, if apparently less obvious alternative.

Requesting microphone permissions for something that would actually be easier without it is also very obnoxious, and for anywhere with GDPR perhaps even illegal if the data was persisted. Maybe this is why it isn't available in Europe?

The guideline is there to avoid escalating obnoxiousness because it trashes the forum.

As opposed to pulling this sh!t? https://news.ycombinator.com/item?id=33494109