Or no, because that takes a clear portion of Fire’s mechanical identity and gives it to every spec.
The reason you use Fireball is specifically because other specs don’t generally have a reason to use it. Being Mages, they should obviously have some base proficiency in all their schools, and using the main nuke/filler as the “base proficiency” means that other specs don’t have off-school spells as part of their moment to moment kit.
You specced Frost, and got spell locked out of the Frost school? Use Fireball or Arcane Blast to fill until you can get back to Frostbolt. It’s clearly suboptimal and you wouldn’t use those spells normally but when you have literally nothing else you can do, they are nice to have.
That’s Steady Shot for BM. BW/KC/BS/CS/etc are on CD, not enough Focus to use Cobra Shot and still use the next KC on CD, so you use 1 Steady Shot to fill the GCD that would otherwise be empty. Arcane Shot is even more niche, you would only use it when you need to proc an Arcane damage effect, if your target has extremely high armor such that Cobra Shot does worse damage, etc.
For SV, it’s even more niche, maybe swapping to ranged to DPS down a caster add you can’t safely Harpoon to, maybe a flying enemy that stays too high to be in melee range, and you swap to a bow and plink away rather than standing there doing nothing but SrS and Wildfire.