Should not the subject be in plural form in order to translated as a general statement, that is, about all artists being painters?
In English, yes. In Hungarian, no. Or at least not necessarily.
Az alma édes. - Apples are sweet. (Maybe think "the idea of the apple"?)
Az almák édesek. - more around "The apples are sweet."
Hungarian avoids using plurals unless it's absolutely necessary. :)