> Try to get a frontier model to write a clever, funny joke which hasn't been seen before.

This is what I refer to when it comes to larger models like Fable 5 being funnier. They are more capable of doing that. They can deliver that "sudden orthogonal leap from context" of yours more reliably.

It's not a "fundamental inability" and never was. If you crank the scale up and a capability appears, "current architecture" was never the problem.