yeah, they did some sideways stuff with spells in this game. in theory it's supposed to streamline stuff but the reality is that it allows you to do things like that. it defines class spells in only the most loosest of terms.
on that topic, i appreciate that they are wanting people to not feel so overwhelmed by spell options, but i also hate that it chooses your pact of the tome warlock spells for you. man, i don't want that whip spell. or vicious mockery. guidance is nice, but only because the people i'm playing with didn't pick a class that has it, and even then, there's that necklace that has it. i want to pick SPECIFIC spells. boo