The problem is if you do this, you have to come up with a word for people who don't eat fish, but do eat insects and crustaceans, and people who don't eat them, but do eat jellyfish, and people who don't eat them, but eat (or more realistically, use the corpses of) sea sponges. And then there's people who never eat it, people who eat it but only if otherwise it would get thrown away, people who eat it but only if they're sure the animal was raised ethically, people who will never eat meat but only eat animal products if it was raised ethically, etc. It's really not worth having overly specific words like that, and nobody is going to remember them.
Yeah, bro decided to rant against half the English language and pretty much all scientific terminology. I'm just sitting back here with the popcorn watching him dig his own grave.
Definitions are approximate. Defining "man" as "featherless biped" is good enough for most situations, but a plucked chicken isn't a man and someone who lost a leg still is.
Sorry. I thought the problem was that definitions are ultimately approximations to help you understand the meaning of the word. Checking it again, the moral was actually that Plato forgot to add "with broad nails", and once he had that he had the perfect definition of a human that everyone can always use.