Just because you are not legally required to help your new spouse pay off her loan does not mean that it does not affect you.
She'll be spending time-and-or-money paying off the loan when she could have been contributing to the welfare of your family, either as a stay-at-home mom or a wage earner.
and you realize she inherits his huge college and whatever else debts too?
your point is fine for people that don’t get divorced. it’s a moot point for them. but in the real world, which is where we live, where sadly about half of married couples divorce, when people get divorced, there has to be a way to fairly separate assets and debt incurred in the marriage, because it was property and debt acquired during the marriage and belonging to both of them. now that they won’t be together anymore there needs to be a fair system so that neither gets too little assets or too much debt.