Sounds like she just wants a party. People will feel obligated to bring something. So even a diaper shower be better then nothing, or you will end up with random crap. Its done in DH's side, to prep again for the basic like diapers, wipes, etc. I think its too much.
I'm usually a stickler for etiquette, but there's a lot of stuff that just doesn't bother me if the person is grateful and appreciative. And honestly I've attended a lot of baby showers for people who weren't having their first baby so I never knew it was "wrong" until the Nest said so.
I know people who just never send out thank you cards, but they are obviously grateful for what they receive and sometimes call or text me to thank me for something, so I don't mind doing nice things for them because I know my efforts are being appreciated. The people that piss me off are the ones who act entitled or just never show any kind of appreciation or reciprocation. The people that ESPECIALLY piss me off are the ones who raise bratty kids who always want more and never know to appreciate what they have, or thank the people that constantly go out of their way for them (especially in cases where other people HAVE to go out of their way because the parents are too damn lazy to do their jobs as parents).