It sounds that way, but really we've only learned of 2, and both are held by guild masters. All the lower thugs know about it because their masters aren't selfish assholes, but they can't do anything about gaining it. That's why everyone can talk to Akatsuki about them, but it's not like everyone has one. Most people training there are probably from a fighting guild of some sort, so our perspective is skewed there in terms of the common knowledge or access to Teachings.

It was a big deal back ages ago when Shiroe left to fight, but it's been some time now.