Honestly if you're going to use SmashPass I'm assuming you're at least going to do it right and run Dual Screen support (Uxie anyone?), so the defense drops on a second SmashPass are kinda irrelevant. Besides, priority in NU isn't too concerning for recipients like Feraligatr and Slurpuff who have good natural bulk and aren't weak to any form of priority barring Hariyama's BP in Slurpuffs case. Most teams don't have double priority, so even if you have to take one hit you sweep regardless most of the time. Also what's going to phaze Gorebyss out? Rhydon? Steelix? Dragalge? You can literally just Sub on the Dragon Tail (if you skip out on Ice Beam) and pass out safely to anything. I prefer to run Sub because it gives autowins against people that try to status the recipient, it's pretty good. Haze Cryogonal is pretty awful, plus you want Freeze-Dry, HP Ground, Recover, possibly Rapid Spin and Ice Beam for a stronger STAB. Not much room for a situational move like Haze. Offensive pressure is also an iffy argument, Gorebyss can take pretty much anything that's not Electric or Grass and it turns out those attacking types are rather uncommon in NU. With Screens up it even tanks those, so yeah. After it Shell Smashes the tables are turned around too; odds are your mon can't take a +2 STAB Hydro Pump so there goes your offensive pressure.
I'm not saying that SmashPass is necessarily broken, but the arguments against it being broken aren't really convincing. As for saying that other setup sweepers can do the same thing, well it's not that simple. Stuff like SD Gatr at least has checks after it sets up. But what beats a Kangaskhan at +2/+2? You could say Gurdurr, but if your opponent has a Gurdurr you can just change the recipient to Slurpuff or another sweeper. That's the problem with SmashPass teams, they have multiple recipients and it's impossible to counter them all after a SmashPass because you just pick the recipient according to your opponents team. I think it's at least food for thought, possibly another suspect.