Any combat-centric franchise will develop power levels, given enough time. People want a tier list, a scouter, a number on a bounty poster, or a midichlorian count.
Tying it to bloodlines is a lazy model, but also gives you loads of popular tropes for free. Glup Shitto Jr will be relevant from appearance 1 due to inherited power levels, and then you don't have to devise a bunch of complex worldbuilding and backstory to show how a 100% new character got the caprice of the fates.
Are there any stories where magic powers aren't inherited? I can think of Frieren and The Magicians, but I think that's it? My LotR knowledge is limited, but I don't recall magic being genetic. Although I don't think many mortals in LotR can even perform magic.
One of the sequel trilogy hinted towards putting away the space calipers with that scene of the random kid force pulling a broom but then the next one made all the named force users part of the same couple of families again
