On one hand, I can see how parents--especially if it's a large family--want to let everyone know, and it's not necessarily a ploy for checks!
On the other, as someone who had to address invitations to people who I know didn't give two flying shits about my graduating from college, I see how it's a waste of time to send and receive an invitation for an event you have no interest in attending. I wasn't even interested in a gift--it would have been nice for one of my father's ookabillion brothers and sisters to even acknowledge that I was graduating from college.
They won't be receiving wedding invites, BTW, even if it means I have to pay them myself.