Earlier quoted context omitted.
Not necessarily dark though... as an app developer I'd actually really want to hear the feedback from the people who dislike my app. As in any business, oftentimes the most disgruntled customer is the one that can provide the most useful feedback. An even smarter way (in my opinion) of getting 5 star reviews is by showing the dialog only after x hours of use. Users most likely to rate badly will have the app uninstal…
The dark pattern is that you're biasing your review rating by not taking negative users there.
I can see how you'd see this as providing a positive bias, but I see it more like getting a chance to see if you can't help the customer out before they give up on your app. It also reminds the customer that there are people on the other end - so even if the issue can't be resolved, and you still get a one-star rating, the level of vitriol seems likely to be reduced - something all too easy to forget when angry-reviewing.
Of course if they just take the feedback and dump it, that's a different story - but again, I would think anyone with that experience would still leave the negative review.
TL;DR - too many downloaders use negative reviews as a combination support request and cudgel. I think this is a reasonable defense against that.