I’ve never heard that before.
And I found out that you are mistaken.
From the dictionary:
Someone who’s vulgar has bad taste, and could also be called unrefined or unsophisticated. Your snobby neighbor might mutter about your family’s vulgar taste if you paint your house with rainbow stripes.
From the Latin vulgus, meaning “the common people,” vulgar is an adjective that can describe anything from the sexually explicit to the merely ugly and crass
“Someone who’s vulgar has bad taste, and could also be called unrefined or unsophisticated. Your snobby neighbor might mutter about your family’s vulgar taste if you paint your house with rainbow stripes.”
When I was young, my father made sure that all “vulgar” people were sent around to the back door, if they were sent to any door at all! Fifty years later and the vulgar are calling the shots because politicians told them that their low ideas and common opinions count for something.
Salvation, it could be that the poster had confused “vulgate” with “vernacular” which would indicate the common language. That’s what I take the post to mean although my assumption might be incorrect.