Why aren’t we using paper ballots?

After reading this, I hope that Illinois has their plan to protect voting machines in place by mid-term elections.   I do wonder why we haven’t gone back to paper ballots.  We use them where I live, but it doesn’t seem Illinois has plans to go that way.

https://www.motherjones.com/politics/2018/07/the-midterm-elections-are-in-serious-danger-of-being-hacked-thanks-to-trump/