Sure, but the vast majority of taxpayers just have W-2 income, and that's it. Even for many of those who have more, it still can be done automatically (1099nec, 1099misc, 1099r, 1099b, 1099div, 1099int, etc. are all filed with the IRS already).

Even if 20% of taxpayers still had to do their own returns from scratch -- which almost certainly would not be the case; virtually no one would have to do them from scratch -- automating it for the 80% would still be incredibly valuable. Even with a manual check/amend/approve step. It would save taxpayers tons of time and billions of dollars of tax-prep fees.