It doesn't matter what you're writing, using plain language doesn't mean you're dumbing it down. It makes it easier to read and understand what you're trying to say. You can take corporate jargon as the opposite of this. It can be vague, different people will have different definitions of certain words.
https://www.grammarly.com/blog/writing-techniques/plain-language/
You can talk about the most complex topics with people as long as you know how to explain them in an easily digestible form. If you look at the titles of many scientific studies they will have long and convoluted titles that sound impressive, but in actuality could be refined into something much shorter and easier to understand.