Alectai never said that. People are simply assuming it.Wasn't one of the larger points of taking Sorcery now that us being able to teach Sorcery as well could massively increase the amount of mortal Sorcerers we produce and therefor give us effectively loads of additional Emerald Countermagic to spam?
Sure, Sidereal Sorcerers in sufficient numbers could still outcast us if we get to Celestial Circle Spells, but for now we are neither going to face Sidereal Sorcerers in sufficient numbers nor is anyone voting for the Celestial Circle in the hope of doing so, because we are still in Chapter 3.
Personally, I want to get good at the stuff we are unique at, not the stuff that Sidereals will know better than us and how to counter. It has been a very, very long time since someone has had to fight an experienced dawn general. Far less than fighting Sorcerers, even 2nd circle ones.