So what happens when, for example, you're trying to get a home loan to buy a new house, and the loan officer is an older person who doesn't use texts? (This is something real that recently happened to me, and for which a phone and voicemail were indispensable.)

I find that while I can do what you suggest for friends and family, there are just enough situations where I can't do that, that I need to still have voicemail. Doctors offices that robocall to remind you of an appointment are another one. The occasional lawyer, or other professional who have a particular way of doing things. Getting rid of phone and/or voicemail just isn't a realistic option for a lot of people.

I disagree, people have used phones without voicemail for decades, they know they can retry. And when I miss a call from an unknown number I can easily look it up if I'm expecting important calls. There are also apps that helps with that, showing who called you even when it's a new number. About robocalls from doctors and pharmacies etc I also manage those comms via email, I take care of telling doctors and pharmacies to give me an electronic prompt, most have a computerized system that does that anyway. There might be people who need voicemail, but I don't buy that it's so common, it's more about people being used to it and not knowing they can turn it off.