It adds at least one more level between the cache getting reported as having a problem, and the cache getting fixed. Probably more than one layer, depending on circumstance. We've already learned that Mom can't be bothered with reading NMs. So that leaves the job for the person who lives way too far away to take decisive action.
In my world, NM = Go fix, post a maintenance note.
In their world, NM = Call Mom, wait for Mom to fix, (Mom might have a life, so not sure how long that will take), get message that all is well, post a maintenance note.
It's why I'm not keen on cachers who place stuff they can't maintain themselves.
Also my mom has a life but when she agrees to take care of something for me, she follows up on that in a real good manner. I have once had a NM on a cache that she maintains for me. When I got the message for that, it took me about 1 hour to call my mother. 30 mins later the new log was in place and she called me back. The next day a owners maintenance was posted. I can not claim that she will be doing this as quicly every time. I could be unlucky. She could make dinner/ have visitors/ throw a christmassparty/ cuddle in bed/ be on vacation/ whatever. But so could I. This time I was the "lazy" one as I did not get to log that the new log was in place untill the next day.
It is not wheter you maintain a cache by proxy or not that is decisive for how good the cache is mainained. It is if you can trust that proxy (most moms are trustworthy) and how serious you take the CO responibility.