I always thought it had to do with avoiding ambiguity. By using a specific word with a specific meaning, you don’t need to expand on the context. I think I read that somewhere a long time ago and just accepted it.
It is pretty much this, same reason lawyers use “legalese” in contracts. That word has an accepted meaning, when used the meaning is clear to others in the field. You don’t need an extra document to define each term as it is expected that others in the field will understand the language used.
In saying that, sometimes it is just complication for the sake of complication.
There is a saying, usually attributed to Einstein but could also be William of Ockham:
Everything should be as simple as possible, but no simpler.
People often focus on the first part while ignoring the more important second part. When something is made too simple, you lose the nuance and fine detail that makes it a useful concept. Not everything can be ELI5’d, somethings are just really complicated.
You don’t need an extra document to define each term as it is expected that others in the field will understand the language used.
For lawyers, it’s the opposite, actually. Lawyers are overly cautious and choose to explicitly define terms themselves, all the time. If they can reference a definition already in a specific law, great. But they’ll go ahead and explicitly make that link, instead of relying on the reader to assume they know which law to look up.
So any serious contract tends to use pages and pages of definitions at the beginning.
Imagine programmers being reluctant to use other people’s libraries, but using the same function and variable names with slightly different actual meanings/purposes depending on the program. That’s what legal drafting is like.
