Compatible sex drives are absolutely necessary for healthy relationships in my opinion. This is just my thoughts on staying in monogamous relationships because that's all I have experience with, but I can speak from experience on having mismatched drives and having it affect the relationship. I have always had a relatively low sex drive. My last boyfriend had a much higher drive than I did. It wasn't fair to me to always be pressured into having sex when I didn't want to, and we were mismatched because he wanted to have more sex than I did. It caused a lot of other problems because we would get together, he would try, I wouldn't be in the mood, and it would literally sour the entire weekend sometimes.
So I think that sex drives need to be compatible in long term relationships. Not being so can lead to a lot of resentment on both sides.