Blizzard has the data. If that were true then I highly doubt they’d spend so many resources developing raids. WoW is a lot of things to a lot of different people, but raiding is Blizzard’s money maker.
The only thing I agree with you on is PvP. Blizzard is not satisfied with people who don’t do “all” the content. If they just let PvPers PvP and PvEers PvE the game would be better.