That's because it tastes like toothpaste. Way back in the day when there weren't too many options, there were only one or two brands, and all of them tasted like mint.
I think toothpaste has a stronger taste though. MCC icecream is more pleasant tasting...and creamy...and you get those crunchy bits of chocolate. Mmmmmm! Always thought chocolate and mint made a good match.
Root beer.....that tastes more like cola colored fizzy toothpaste to me.