Of course DOTs can’t crit. I’m a lock, I know this well. Still, Int is a decent stat for a mage because of the mana and the other spells which do crit.
Pretty much all AOE is 1/3 your spellpower. That’s one good reason you should only use it when there are 3 or more targets. Spellpower is still incredibly good for someone doing AOE.
The information is not just a “copy-paste”, there are very valid reasons for these choices. A frost mage AOE grinding will most likely want to follow that guideline I posted, other types of mages will want a different mix.
Stam doesn’t do much for a mage, especially frost ones. They have lots of escapes and, outside of PVP, they only need Enough Stam to survive a few good hits.
Spirit is useful but they get free food and water. It’s mostly better to use those, except in extended boss fights.
Int is great but, as you said, Blizzard doesn’t crit. So you’re mostly getting it to have enough mana to get through an encounter as well as crit for the spells that do that
Spell power is top. You kill faster and use less mana doing it. No matter if some coefficients aren’t amazing, spell power still does a ton.