The series get more realistic as it keeps going

Metal fight: Final battle had the whole world watching and had the earth and every place in the universe at stake

Zero G: Final battle had the future of one sport at stake

Burst duel layer: final battle would make certain people happy and others unhappy
Then the God series throws all of that progress under the bus, with Snake Pit and super blader engineering in giant vats and whatnot. Spectacle creep is a very difficult thing to avoid in modern fiction. But seriously, I don't think any of this matters anymore. Beyblade tournaments are just subplots to keep the "power of friendship" plot moving. So yeah, I don't think that spectacle creep is too much of a problem, as long as these subplots don't get in the way of figuring out the relationships between the characters. Realism does not directly affect the quality of any story. You can have literal gods duking it out with beyblade toys and no one would bat an eye, because that's not the point. As long as the story elements don't destroy the immersion, the scale of the conflict is not an issue in itself.