We get this so much more these days, probably starting in the last 2 years. People quit by just ghosting us completely. Almost always younger people who do it, they just seem adverse to confrontation. It's such a lame way to quit, but whatever.. I'm just Gen X'er bitching about the new generation like my parents did about us.
On the hiring front, we contact everyone who applies at least with a call, and if we don't contact we e-mail. We typically offer on the spot these days, as opposed to waiting... then again I'm hiring entry level. A lot of times they say yes, then ghost us after sending paperwork. Or do paperwork and never show or contact for orientation. It's so common these days we don't even blink an eye over it. It's almost expected we are ghosted by over half the offers we give out.