Article is from 2014 where this was more of a valid concern. These days I don't think people send email for anything other than external communication with businesses. And only in western countries.
Most people are on Facebook Messenger or Whatsapp or Signal or a dozen similar platforms. I try to use Signal for most communications but have friends and family that won't move to it, so I also use Whatsapp or plain SMS with them.
The only people who use RCS to contact me are businesses sending notifications or spam.
Unlike e-mail where I do get personal correspondence regularly.
I don't expect my experience is typical, but I don't think yours are either - we all live in bubbles.