Maybe i'm misremembering, But I believe there has already been a suggestion for a Soul Link NPC, which was rejected
But anyways, not only the super novice one but most, if not all class soul links are basically useless because they only buff/enable 2nd class skills, we're talking about a pre-renewal mechanic, the only one that can be somewhat useful is SG granting 100% defense ignore and crit in every attack, but is also kind of unpopular because of the handicap of draining your own hp
just changing a class restriction seems much simpler, i'd say