I'd just assume it was because there actually are relevant bounds to power, otherwise the Accursed would have had Graham's number or
BB-20 (or 200, but it really really doesn't matter at that point), or if we want to get really bad,
TREE(7) (again, you could use 3 or 20 equally well, they're all horribly intractable and really solidly larger than anything computable is going to practically get, unless I misread my math). If we want functions which grow quickly, they're all over. The fact that the Accursed only has doubly exponential power means he's actually an achievable goal, for the proper definitions of achievable --- if anyone were to do something like septuply exponential, much less uncomputable values, it's just hopeless rather than a value people can theoretically reach via some horrifically unbounded infinite loop. Very few infinite loops are actually going to grant uncomputable levels of power.