Yes you are missing something.
First, fixed blade knives are not legal to carry in all jurisdictions. In some areas, the government doesn't want ordinary citizens to defend themselves from criminals. This is political. The government wants the monopoly on the legitimate use of force.
Second, there is a variety of human so timid and removed from reality (sheeple) that everything that they see that even remotely resembles a weapon causes spasms of fear. Unfortunately, these people vote, and they vote for the politicians described above. Since most of us, that is, people who are not prepared to depend on the government for our safety, either don't vote or engage in political activity for our own benefit it dosn't pay to alarm the sheeple.
Third, if you work in an industrial setting carrying a neck knife openly may be ok, but for many people, concealed carry for last-ditch defense is a common way of carry. Even if the short blades of most neck knives are legal, you don't need the hassle. Also, hideout pieces are best as surprizes. HTH
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The thorn stands to defend the Rose, yet it is peaceful and does not seek conflict