system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:What’s the purpose of long words which have short, simple equivalents?
gpt
In English, words do not need to have purposes.  You cannot take a word to court and have it banished for shiftlessness and vagrancy.  However, writers can have a purpose for using particular words.  Often the purpose for using longer words is clarity and precision.

Short words tend to accumulate a lot of different meanings.  "Have" can mean "possess", "obliged" (or "required", or "must"), or just be a helping word to change the tense of a verb.  "Used" can mean "formerly", "accustomed", or "utilized".  Having too many short, simple, but ambiguous words together in the same sentence or paragraph can render the entire thing ambiguous and opaque.  This is particularly the case where the intended audience includes people with limited experience of English.  While the words might be short and simple, figuring out what they mean through context is not.

There is a famous joke/pun:

> Time flies like an arrow.
> Fruit flies like a banana.

This is based on the ambiguity of both "flies" and "like".  If it were written like this:

> Time propagates similar to an arrow.
> Drosophila appreciate a banana.

then there would be no ambiguity.  There would also be no humor, but sometimes ambiguity is no laughing matter.