Do people answer random phone calls anymore? I basically do not answer the phone unless Caller ID matches a (good) friend, or I have a scheduled call in my calendar.
I also use Google Voice to transcribe voicemails (I never listen to them). The transcriptions are never perfect, but I usually get the gist. It's much more effective to hang up and send an email or text, but if someone just writes "call me" without saying why, I usually do not call.
And this is coming from me! A middle-ager! Imagine what happens when you cold-call an actual millennial: you've just advertised yourself as someone who has not adapted, probably will never adapt, and possibly doesn't ever want to adapt.