Why do I need to provide my AGI from the previous year, as part of the process to e-file my completed return?

It is to help prevent someone else from filing a tax return pretending to be you.

You do not need to have your prior year AGI to mail your return.

I couldn't print the forms, and didn't have access to my prior year AGI. I e-filed last year but the online reference says there's no record in my account.  There should be another way to verify myself.