Champ picks on Dominion are extremely impactful from what I've seen. There aren't many that are straight up overpowered, but there are a very, very large number of them that are game changing. Pretty much every champ that is at all good on Dominion really. Thus, if you want to win, you have to do some counterpicking, Blind Pick is like rolling dice pretty much.
Just had a match where I counter picked Heimer with Smite Nunu and proceeded to eat his turrets and snowball him to make him completely useless for the whole match.