Same reason as why dictionaries have multiple definitions for a single word. The specific meaning of a word is dependent on the context it’s used in. Languages also evolve as we discover more about the world we live in – new words are created and old ones get updated to better fit reality.

Sometimes people willfully ignore that in an attempt to force a discussion to a conclusion that isn’t true. They don’t like nuance or context, because those are the death of a bad argument.