If someone has to have first hand experience using the diapers, does that mean a diaper making WAHM can only make diapers as long as she has children in diapers? Once her children are out of diapers, does that mean she can no longer try new fabrics, or tweak her design at all based on customers' experiences alone?
I'm not so sure that day to day experience is so important. Of the diapers that I've purchased, I have some I love, some I hate, and some that do the job well enough so that I don't hate them, but I'm not dying to have more, either. Out of these diapers, I see raves all the time with people loving the ones that I hate and occasionally hating the ones that I love. I don't think I've seen a single diaper that ONLY gets negative reviews, or one that absolutely EVERYONE loves.
My point: a non-mom, with a little research, could produce a diaper that would work well for a lot of people.
There are a lot of men who design women's clothing, and I certainly don't expect them to wear the clothes to see how they fit, or even that they must live with a woman so that they can see how the clothes hold up for day to day use. (I do wish that every man was required, at least once, to wear a bra and high heels around for a couple of hours, but that's another post.)
In the end, it doesn't matter how well a diaper works for the WAHM who made it, her testers, or her scores of loyal customers, if it doesn't work in MY house. Now, a mom with diapering experience should have a better chance at success than a single childless person, but I wouldn't let the fact that a person didn't have children stop me from buying their diapers if they worked well for us.