Speaking as a Southerner, this sentence is so on point.
This is jarring to people who cannot receive a no, or who cannot articulate one.
This is abstract, but stay with me here
I'm also Southern, and I think that the inclination towards that kind of belligerent helpfulness comes from trying to figure out what your guests want, and making sure they don't have to ask you for anything.
in my experience the response is "we're all good out here, but thank you!" -- which is classic Guess culture
In my own experience, I once had an obnoxious colleague who asked "How was your weekend?". I didn't like the question because one, I don't like to talk about what I do / did in my spare time, and two, it was leading because the guy was really really eager to talk about HIS weekend, but... I didn't care, or else I would've asked.
If it's said as a greeting, "how y'all doing?" usually means "how are your family?," which also tends to be meant very genuinely.
Even outside of a host-guest dynamic, I do think Southerners tend to care more about pleasantries; when they ask about your weekend, they're a little more likely to really want to know.
Of course, this is all very broad strokes based on anecdotal experience. Plenty of cold/self-aggrandizing jerks in the South, too!
"yall doin okay?"