What do you think about using Thoroughbreds for dressage?

Are they capable of being good dressage horses, or are they simply not suited for some of the movements? I ask because I've always loved riding Thoroughbreds and I find that a lot of them are quite good at getting round. Personally I think they're one of the most intelligent breeds as they learn so quickly, yet everyone disagrees. They say they don't like using TBs for dressage because they're harder to get the form correct and execute some of the movements. Thoughts?