Given how nobody properly understands LLMs, I doubt that they are intentionally designed like that. But the effect... yeah. I can see that happening.
(By the way, are you confusing affordance, the UX concept, with affordability?)
Nobody properly understands dog brains either and yet you can still train a dog to sit.
You can intentionally market the use cases without knowing exactly how they work, though. So it's intentional investment and use case targeting, rather than directly designing for purpose. Though, the market also drives the measures...so they iteratively get better at things you pour money into.