I would imagine refuelings are limited because at some point you are going to need to inspect and potentially replace some of the critical components that have been exposed to hard radiation. Materials that we would think of as stable can degrade in such high radiation environments. Like a large chunk of steel can have its crystal structure disrupted as atoms get displaced by high energy neutron strikes or other fission fragments, changing its material properties and making it weaker or in most cases more brittle. Localized impurities can also be formed by either alloying elements in the metal being displaced the same way, or from transmutation of atoms into other elements from the strong radiation. And along with disrupting the material strength those impurities can cause hot spots in the metal causing more stresses and fatigue and further reducing it's lifespan.

We are actually pretty good at making alloys and materials today that can resist radiation problems better and more predictably these days, but there is still a bit of randomness from manufacturing variables that means you need a pretty large safety margin to prevent problems. They probably would work for a dozen refuelings, but the consequences of a reactor breech are too high to not have a massive safety margin. And maybe after they ran these for a few refuelings and inspected enough of them they could bump up the refueling limit before inspection or replacement a little.