Yeah-- I think blaming dark patterns on A/B testing is like blaming thermostats for chilly houses. A/B tests just show if one thing does more of something you're testing for than something else. If you're just testing for "conversions" then you're going to make websites like booking.com. If you're testing to see if users are more stressed out by one situation or another, or testing to see if expert users are stymied by some interface abstraction designed to make things easier for less sophisticated users, then that's totally different.