Dullard gave very good explanation. He also pointed out that getting more primary votes does not result in winning general but on the contrary. I would have never guessed that!
I would like to get across that I think the primary vote totals are meaningless rather than contrary. I use the contrary example as emphasis as to why not to rely on primary vote totals.
As population grows and the politics get more partisan, primary vote tallies have been increasing. But it can't increase on both sides and then have both sides use that as proof that they will win (the GOP had the most primary votes ever and the Democrats had the second most votes ever, thus both sides could try to claim victory somehow from high vote tallies). No, it means there are more primary voters, and that is the extent of it.