Abusing drop rates like that could result in getting regulated as gambling. No gacha game company would ever want that. You'd gut your customer base (good-bye, kids and teenagers that drive older whales to spend real money) and would basically turn your entire gacha system into an open book. (no more hiding "pity" mechanics)
It's why Blizzard noped out entirely and killed their loot box system in countries that regulated it as gambling.