Not sure if that is a joke or not. But if it isn't I think you greatly underestimate how many knew how to use a computer 10 years ago. Office workers aren't a big enough share to say that more people than ever know how to use a computer.

What category used to have a computer 10 years ago but doesn't now?

10 years ago people used computers for things that they use smartphones for today, like doing banking etc. So the category is everyone who feels they need a smartphone today but doesn't feel they need a computer today.

Assuming this is true. What is the benefit to society or individual of blue collar workers owning computers in order to do online banking?

Seems like a great benefit that they don’t have to deal with all the unnecessary complexity.

Being forced to learn enough computers to log on to your bank doesn’t make you more employable.