John Doe writes:

It could mean that they are showing off, or maybe they don't
understand that writing is to communicate with other people.

The better the vocabulary, the more precise and efficient the
communication.

It's impossible to know another person's vocabulary level unless he
indicates his level in some way. People with large vocabularies have
a natural tendency to use those vocabularies to the fullest and do not
necessarily realize it when and if they exceed the recognition
vocabularies of their interlocutors.

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Transpose mxsmanic and gmail to reach me by e-mail.