I knew I explained that poorly. What I mean is that, in comparing "y'all" to "all y'all", a simple "y'all" is "you guys (and maybe me)" while "all y'all" is "you guys and not me".

Grammatical constructs can have a lot of variation between languages, and there are certainly nuances that can't be expressed in English the same way that it can be in other languages. One thing we lack is a nuanced sense of past, while other languages have baked in ways to express recent past or distant past (e.g. Bantu languages).

My proposed interpretation regarding "all y'all" is not academic, just a native feel, and I'm sure other native speakers could disagree.