Science

True story: in the early 00s, my company was acquired by a Large Silicon Valley Company. LSVC sent a "business integration" team across the country (to Dallas, Texas where we were at the time) to welcome us into the fold. At these meetings, these Perky Northern Californian Women - they were all Perky Northern California Women, for whatever reason - opened with the following sentence:

"We'd like to welcome y....ya.....y'y'y'y'y.....YA UL(!) to LSVC."

Repeated throughout the meeting, the integration team kept stumbling over "y'all" instead of just saying "you" when talking to us. Clearly, someone thought that - being Texans - we wouldn't understand them unless the did.

At one point, one of us spoke up and said something like, "First, thank you for attempting to use our local dialect to talk to us. But, we can understand you perfectly well when you speak your native Northern Californian. Second, by way of correction, the word is just "y'all". Also, if you want to use the plural second person, like vous in French, you may say "all'y'all", but it is optional."

I'd guess it's just not natural to have a missing pronoun like English has since the days of thou (which was the original singular).