I don’t know. But if you’ve opened up the IRS free fillable forms website, and put up the accompanying instructions on your second monitor, and know how to read English, I don’t see how it’s difficult, if you’re income is from a W-2. Everything is kind of labeled and laid out for you.
When I was in middle school (1980s) we did a tax return on paper, I think it was part of a Social Studies class? We were given a fictitious W2, number of dependents, etc. and had to fill out a 1040 and a State return (on paper of course, no computers then). This permanently demystified the process. I think a lot of people who pay HRBlock or similar to do their taxes have never tried to do their taxes manually and are just afraid to try.
I have always done my taxes myself, on paper, even years when I had capital gains, education credits, 1099s, and small business (single member LLC) income. It's a bit time consuming but not difficult per se.
I believe that's only for filing a federal tax return, and for filing your state tax return you still have to either use a tax preparation website or do it on paper.