Do churned users actually reply if you email them directly after dropping off?

Dashboard funnels and drop-off charts will tell you where people left, but they never really tell you why.

We tried staring at drop off steps for weeks trying to guess the issue but nothing beat just emailing people who bounced on day one.

Out of fifty quick casual emails asking what went wrong, only three or four replied but those few replies completely exposed a broken signup step we were completely blind to.

For anyone doing user research, what is your trick to actually getting a response from someone who already walked away?