I just hosted a small house concert last night for about 20 people; the age range was 18-50, I reckon. I put out a sheet of paper with spaces for names & contact info, for folks who wanted to be notified for future shows, and intentionally left the contact method open -- I figured if they wanted a group text, or a FB msg, I could do that.

I was surprised to find that every person who signed up wrote their email address.

So you may just might be right.

Granted, this is a rural area (West Virginia, US) and there's far less incessant use of smartphones and the like. So my experience might not apply to more urban places.