That’s a good one! Sometimes I blame Google. I wrote a rant some time ago about Google’s definition of “marketing” and the actual definition of marketing, because Google’s definition was inadequate and incomplete.
But in the case you mention, Google actually has it right. lol. I think you’re right — people like to sound smart and/or sophisticated. I suspect that goes back to English class in school, where vocabulary is praised.
When I was in 5th grade, I had a 12th grade vocabulary. It took some time to realize that a big vocabulary is beneficial for understanding what I’m reading, and teachers liked it in school, but it is not so useful when writing.