I'm a 50-something and my Mom with her Mac manages to get infected with browser-based malware. And she's pretty careful. But sometimes those "update" notifications look real to her.
Chromebooks are probably the single best option for a computer with a keyboard. I wish the chrometops were a bit more compelling, as I'd probably switch my other grandmother (ubuntu 16.04) over. She has one program she plays a lot (since 1996) which runs under WINE.
Because those apps shouldn't be able to be opened unless the author has code signed them.
In which case if they are malware then just report it to Apple and they can centrally block the app.