I don't necessarily agree with the idea that stored power NEEDS to be banned, but we have already seen the idea that moves don't need to be banned on a majority of users to be banworthy or uncompetitive (this gen especially). The push to nerf Tera by removing Tera Blast is something that has been put forward by high level players and council members, and you can very reasonably make transitive reasoning from that to Stored Power as a move. It encourages cheese and matchup fishing to a higher extent than almost any other move.You can say Stored Power is annoying, and I'd arguably agree with you on that, but it's not something that's banworthy on it's own. There's a plethora of counterplay to Stored Power specifically, however we see cases of Pokemon being problematic when they have aspects in combination with it.
- Hatterene is only as good of a Stored Power user because it has Magic Bounce, an insane ability, typically with support from Grassy Terrain + Grassy Seed.
- Espathra is only as good of a Stored Power user as it is because it has Speed Boost, Calm Mind, Substitute and is an effective user of Tera Blast.
- Magearna is only as good of a Stored Power user as it is because it has an insane defensive typing, Shift Gear, Calm Mind, and Soul-Heart.
- Manaphy is only as good of a Stored Power user as it is because of it's acces to scald, Double Dance, a second very viable set with Tail Glow, which forces guessing games, all with a very potent defensive typing
- Cresselia is only as good of a Stored Power user as it is mainly because of Levitate, which is very beneficial in the current spikes heavy meta, but also insane defensive stats.
- Polteageist is only as good of a Stored Power user as it is because it has Shell Smash, usually in conjunction with Psychic Terrain as well
You can argue that you dislike the move Stored Power, so it should be removed, but the abusers of it all have various elements on top of Stored Power that makes them able to abuse it so effectively. I'd only really go so far as saying Magearna, Espathra and Manaphy are the truly broken pokemon, the others are definitely manageable and beatable with a lot of counterplay.
Ausma had a great post explaining this reasoning on Tera Blast here. The overall viability of Stored Power within the meta is definitely lower than Tera Blast, but there was still one mon banned (primarily) due to each move (Espathra and Regieleki), and similar numbers of high level abusers (Kingambit, Dragonite, Iron Moth vs Manaphy, Hatterene, and Cresselia).
Side note- Power Trip would probably be a better move than Stored Power if it had the same distribution, it's only not talked about due to the fact that the only mon that has even a meme set that can use it is Corviknight.