I guess there's some logic to thinking that smarter people know more words so they use bigger ones. Maybe people who wish they had more education imagine some of the education they missed included vocabulary.
In my experience, people considered smart use common words to avoid distracting from their ideas and meaning.
Likewise, in business people use jargon, I think to imply authority or mastery. When I teach entrepreneurship, for example, students forget how to change. Instead, every change becomes a "pivot." Every presentation becomes a "pitch." Every description becomes an "elevator pitch."
I find it more annoying than people who say "utilize" instead of "use" and "neuroplasticity" to describe "an ability to learn." More than annoying, it's distracting---from you and what you're saying.
Again, in my experience, the leaders in a field use regular words. With nothing to prove, they prefer that others understand them, which big words and jargon undermine.
Big words reveal more than a lack of education
I used to think the issue was education---that people with less education tried to imply they had more with big words, while more-educated people used regular language to avoid distracting from their meaning.
But I know a lot of people with Ivy League educations and they needlessly use big words too, so I don't think the issue is looking uneducated. I've concluded the distinction is people feeling insecure about their intelligence.
They imply insecurity and neediness
In other words, I find using big words and jargon implies you feel insecure about your intelligence and education. The practice makes you sound needy.
As much as I wouldn't want people to see me as unintelligent and uneducated, I'd prefer them to people seeing me as insecure or needy.
What trait do people recoil from more than neediness? Do you want to repel people?
I recommend favoring regular words. Communicate your ideas and meaning, not your insecurity and neediness.