The simple answer is that it's code-speak, and it's designed to make people feel better about their jobs and salaries. Speaking in plain English makes many things seem childishly simple—which isn't good for anyone's ego.
Obviously many fields are specialized and technical, and complicated language is the simplest way to get ideas across, but I think we can draw that line pretty clearly.
EBITDA is a meaningful term that communicates a lot of information. "Synergy" is useless, and is essentially an SEO tag for an idea you want people to pay for.
I'm not saying that different disciplines don't have jargon that is useful, I'm saying that a lot of jargon is not useful.
Obviously many fields are specialized and technical, and complicated language is the simplest way to get ideas across, but I think we can draw that line pretty clearly.