Sure you can move the goalposts here, but OP clearly meant to say software tasks cannot be estimated because people only work on novel problems, since everything else is "not worth doing" (what a massively privileged thing to say by the way).

Just because something hasn't been done the exact same way you're doing, that doesn't mean you can't apply a generic solution. I have never changed a tyre on an SUV before, yet I do know how to do so based on my previous experience with a sedan. The same applies to a car mechanic; even if I bring a brand new car to the workshop they have never seen before, I can and should expect them to be able to (at least roughly) estimate how long a tyre change is going to take.