Certain of their spells got kinda fucked up... Mostly debuffs. But there's a solo run mage on the web for BG3 I think. And yeah granted " someone did it" doesn't mean it works as it should( Cause someone also finished the game without leveling up).
Idk, I guess it's more a question of difficulty level. When they will be introduced should solve your problem with mages. And use mage armor + mirror image if you struggle with survivability.
