Anyone can learn to communicate in a simpler way, otherwise nobody would be able to train a dog. However doing so in most communications is not only tiring, but also has some pernicious psychological effects.
My writing coach always told me “Anyone can say anything if you give them enough words.”
Some people love to use big college words. I think it makes them feel superior. It’s hard to speak simply and clearly.
The real problem is that talking this way is exhausting. As if someone told you that e.g. you are not allowed to use words containing the letter "m". It is certainly possible, but it requires constant attention to something other than the idea you are trying to convey.
Talking this way feels quite different from talking to someone who uses the same style as you.