Not true. Specially denfensive versions can take latios' draco meteor and counterattack with blizzard, stripping away most if not all of latios' health. A priority attack, especially with a good typing like ice, is always helpful. It can also come in on most bulky waters and threaten them, and proceed to subseed, focus punch, or hp fire depending on its set and the predicted switch in.
Also note that weather pretty much defines this metagame. Hail, being the least useful weather, is basicly the anti-weather. It is useful against sun and sand teams as well, even if it can't come in on them with ease like rain teams. You can build a team that doesn't depend on it for their purposes but only to cripple their opponent's weather with hail, which you can't really do with the other weathers- you may run into a team that uses any of the other weathers and if you're carrying that weather to stop others, but not really using it, then they'd have a pretty good advantage over you.
Rain teams carry Ice attacks,and he's neutral to them.
Sun teams carry Fire attacks,and he's 4x weak to them.
Sand teams carry Rock attacks,and he's 2x weak to them.
All weather teams will have SOME way of dealing with Abomasnow thanks to his slowness and mediocre stats.