"Haven't there been some studies showing most people, when presented with a "Enter your email address to continue" modal, just fill out the form and click okay?"

Perhaps. I do it too if I really want the content BUT like many of us, my email address is "wont@tellu.com". Heck, if they make me enter my first/last name (some even do that), then my first name = wont, last name = tellu. So the point is, most of those are garbage bogus data anyway. Why bother collecting ? Now if the study shows that the % of garbage data entered is much lower than correct, then we are on to something