It’s redneck culture from the South from many years ago that lingered on to today through them.

I completely agree that it is a dialect and has rules to an extent, the ‘to an extent’ part being that most people’s criticisms of those using it is that they aren’t actually saying anything, they’re just cursing and using slang to cover up that their speech has no content.

“Sheeeit, nigger! Bitch nigga fuck sheeeeit. Fuck ass bitch nigga.” A lot of what people say when they speak that way is basically that.

You can use it to say things of note, but nobody does, and it seems to have only developed to obscure the fact that someone has nothing to say.