^^^I wonder if it is a function of knife laws. For example, Washington state does not have uniform knife laws, and so each county and/or city or town can create their own knife laws, usually having to do with blade length. I most commonly carry a 3.5" Benchmade triage, and that is illegal in the city that I work, but is not illegal in the unincorporated county that I live or some of the other cities that I travel to for work. In this area, pretty much everything up to 3" is legal almost everywhere, and everything over 3.5" is illegal almost everywhere. So based on that, I can see how someone would think that a 4" knife is a 'big blade'.