I hardly believe the argument that Froslass + Hail is a problem. She is incredibly weak to priority if her sash is broken. Her counters are so incredibly common in this bracket.
Froslass typically don't use Sash. Hax against Froslass typically does not occur over one turn, but over several. It's going to paralyze you and then spam Substitute until you miss / get fully paralyzed, laying down Spikes with the free turns. Spikes are typically worth more than critical hits, and I think quite a few people would be happy to play a 5v6 game if they start with 3 layers of Spikes down.
Togekiss is fine because it can be walled. A Pokemon like Empoleon or Registeel can take unboosted Air Slashes all day and force Togekiss out (or put up SR). Togekiss
can use TWave, Nasty Plot and Roost, but once it starts boosting / using recovery its moves get predictable and you can go to a faster Pokemon to kill it; its speed isn't exactly stellar. With only Air Slash as well its coverage is also weak. A walled Togekiss achieves nothing. Froslass on the other hand can be walled (Milotic / Chansey etc can tank Blizzards forever and ever) but that will typically mean 3 layers of Spikes. In the worst case scenario you can revenge Togekiss, but against Froslass you face the 20% chance of missing. Since revenging Pokemon are typically frail, and since teams typically only have one dedicated revenge killer, missing that 20% can cost you the game. Of course too, if Froslass has already gotten down its 3 layers of Spikes it can afford to die.
You CAN threaten to sweep a hail team with Scarf Heracross or Victini, but only up to a point. A good hail team will have counters to these Pokemon. Heracross cannot Close Combat safely as long as Froslass is alive. Victini can spam V-Create, but it does have some solid counters if nothing else. You can bet a good hail team will have Pokemon like Hitmontop, Nidoqueen, Rhyperior, and similar Pokemon to tank these hits. Both Pokemon are fully vulnerable to entry hazards, not to mention hail, and so they will die eventually. In the worst case scenario there's nothing stopping the hail team from Scarfing a faster Pokemon, e.g. Rotom-F. It's a tight race to sweep before you get swept.
Finally hail teams aren't necessarily stall. There're plenty of offensive hail teams out there that spam Blizzard with Spikes support. To say hail stall is the most effective hail team out there is very narrow, to say the least.
Personally, I'm not convinced hail without Snow Cloak Froslass is broken, but I'm coming pretty close to changing my mind.