Ask HN: Why aren't you using two-factor authentication?

I need to answer this question for research purposes for a product I've been working on: https://www.gauthify.com . I want to be ready for launch (expect a show HN soon) and want to know what people attribute as the primary reason for not using two-factor authentication. Hopefully, we already covered some of the reasons but if we didn't we still want to fix and improve.

Thanks for all the help!