I assume Relic already has a statistic like this (not that they ever do anything with it anyways). I can see no benefit for having the rest of the community knowing these stats though. It would just cause people to pick the most used ones instead of the others because they don't want to feel like they are getting the short end of the stick.
Isn't this already happening?
Its not like many people pick any Ost doctrines without an Elephant or Tiger (for example). Besides, its just showcasing the top 10 or so folks in each doctrine, and your own record on your player card with different doctrines. Would be interesting information. I personally would take it as a challenge to see if I could get a good record with the less used doctrines.