I don't have experience with anyone actually throwing a fit for not insta-replying. But one factor is that for some people not-insta-replying == never replying.

I don't have experience with anyone actually throwing a fit for not insta-replying. But one factor is that for some people not-insta-replying == never replying. Email and text as async communication only works if both parties actually have the processes in place to reply async.