Do we not frequently see that kind of pushback against DIR here on SB, with your example of someone arguing a 7-ft hose is unnecessary being common? I wouldn't call it proselytizing; rather, it's usually someone arguing in defense of some traditional way of doing something when confronted in a thread with the DIR way. If your definition of a non-DIR diver proselytizing is a non-DIR diver trying in earnest to convert a DIR diver back to the way the DIR diver was probably originally trained in their OW course, I doubt we will ever see that, because the traditional ways we were taught aren't generally thought of as making up a "system.""Proselytize" just means trying to convert someone from one belief system to another. so of cousre an agnostic could proselytize; they would just say my belief system is better than yours, becasue mine is right and yours is Wrong.
A non_DIR diver could make fun of a 7 ft hose on a recreational NDL dive, saying, "Ha, do you think you are in a cave and need to share-air single file through some restriction? Anyway, that long hose can get trapped, entangled, allow the reg to dangle and be damaged, and is unnecessary overkill for this diving. It is harder to use and takes more care and training, so what is the point?" Yes, that would be proselytizing; but have you ever heard it?
Perhaps the aspect of DIR that appeals to me most is that it is presented as a system, with the various parts working together. I'm not sure whether that's entirely true, but the idea appeals to me. Anyway, something that is touted from the beginning as being a system is more likely to be the subject of zealotry than something that is presented in a less cohesive way. An unfortunate side effect in this case.