That's fair. But like mentioned below; WoL can do everything she can do (sub-jub Paladin), with better movement (skill).

(Sub-job Spellblade)* my bad.

And also the point of her being a "magic tank" seems meaningless or underwhelming considering her mastery has no effect on most magic skills.

She does have taunt skill in Paladin sub job, take a look once more

That's redundant; because it means you lose the "SPR Buff" skill that y'all pride her for for being a so called "Magic Tank". You seem to be forgetting that setting her sub-job to Paladin causes her to lose "Holy Guard Protection", being a 3* skill of her main job. Without that skill, she's just another regular physical tank (but a plus would be being a non-light attributed tank).

One that has a lower def and hp than most of the other tanks though.

She doesn't really fit as a dedicated "Tank" but she has the ability to be one.
More like a off-tank or bruiser that can resist magic, inflict status, and do good damage.

put her on a team with other tanks or bruisers (especially ones with low mag resist) she will do good work for you

She can use the Paladin's passive even without having it as a sub-job. Stop spreading misinformation and keep your stupidity to yourself.