I hate those too. On the other hand, I've been adjacent to the decision to add them before. You're under a lot of pressure to increase conversion in your onboarding funnel, so you test out moving your email capture up a bit in your conversion flow (ie to before you deliver results) and it works! Conversion increases throughout the funnel! So you keep it. Dark patterns like this persist because they measurably work. S…
Besides putting the business in a negative light for the new convert, I imagine a subset of those would feel more entitled than before. I probably would - if I had to give you something to convert my picture "for free", I would definitely feel entitled to good results. I would be far more likely to complain/badger customer assistance in case of insufficient (for my needs) results.