But it clearly hasn't been enough of an issue in OU to be brought up there, while it is an issue here? There's all sorts of stuff in OU that handles BPass well too, like the omnipresent flying priority.
BP is very overcentralizing in UU. If you pass multiple boosts to a specific poke whether it's bulky espeon, toge or a wallbreaker like LO Nidoqueen, there really isn't much the opponent can do to check/counter them. Even LO Nidoqueen 2HKO the entire tier if it has +2 to Sp Atk, including Blissey
+2 252+ SpA Life Orb Sheer Force Nidoqueen Focus Blast vs. 252 HP / 4 SpD Blissey: 517-611 (72.4 - 85.5%) -- guaranteed 2HKO after Leftovers recovery
+2 252+ SpA Life Orb Sheer Force Nidoqueen Focus Blast vs. 0 HP / 4 SpD Assault Vest Snorlax: 411-486 (89.1 - 105.4%) -- 31.3% chance to OHKO
If you add in hazards, dual screens, Memento support, etc.. then Queen (or almost any other poke) can just plow through teams with relative ease, while your opponent is left squirming and scrambling for options.
Even priority can't even help you...
252 Atk Mega Absol Sucker Punch vs. 128 HP / 0 Def Nidoqueen: 163-193 (46.1 - 54.6%) -- 59% chance to 2HKO
252+ Atk Mega Abomasnow Ice Shard vs. 128 HP / 0 Def Nidoqueen: 164-194 (46.4 - 54.9%) -- 98.4% chance to 2HKO after hail damage
These are just examples, but there is literally nothing your opponent can do. Regarding the deniss team template, you are forced to run the following with
chance to stop the strategy...
1. AV Metagross: 200BP Stored Power is a 4HKO on AV Metagross while it is immune to Memento thanks to Clear Body. Resists Explosion from Azelf. But, Smeargle can Spore you and your only check is now incapacitated.
2. Safety Googles Metagross: Immune to Spore and Memento. Needs to nab Meteor Mash boosts to really break through accumulated possible defensive boosts.
3. Sp Def Rachi: Probably the safest and most reliable check to denisss team. But, must be wary of Spore, just like AV Metagross.
4. Toxic Umbreon triggers Synchronize on Magic Bounce. Needs to stall out with Wish/Aromatherapy and is almost 2HKO by a boosted Dazzling Gleam
5. TrickScarf Pokes (i.e. Rotom, Chandy). Needs to TrickScarf as Smeargle is boosting. Very reliable way to stop the chain, but Tailwind support from Cotton Balls puts Smeargle at a speed above scarfed base 100s, so it can Taunt/Spore.
Does this sound like a healthy meta to you?