I never created an OkCupid account, but I've had someone create an account with my name and pictures for who knows what purpose. Getting it closed required me sending OkCupid my ID and a selfie after a couple of angry emails threatening legal action. No way around it and no way to know what they did with it afterwards.
Considering how long OKCupid has been around, there's a good chance a significant majority of internet-using millennials have had an account at some point in their lives.
It was good. I can't tell you if it is anymore tho
It stopped being good when Match bought them and turned it into Tinder 2.