This is an interesting theory, though I still can't understand why this would be the case. There are likely many people whose income has increased dramatically but have received timely biometrics notices. When we initially applied for DACA back in 2012, we were asked about our income as well. I can only speak for myself, but my income was very low because of course, I didn't have a job at the time. When I applied for my first renewal, my income went up significantly because by that time, I already had a pretty decent paying job. (My biometrics notice came within days after receipt back in 2014.) I imagine this is the case for many others.