MoonSong
Rules-lawyering drama queen but not a munchkin
I think the errata is to control how potent the spell is against one target, not many targets. Before the errata, if an 18 CHA sorcerer cast scorching ray and directed all beams at the same target, that is +12 damage. That is significantly better than all other 1st level spells.
But it comes at the cost of ten known spells the other sorcerers get(or all of the fancy toys wizards have but sorcerers can't do anymore). Scorching ray is a 2nd level spell, and this happens only after 3rd level spells become available. without this stacking, dragon sorcerers are basically crippled.