That is an excellent question & one that a lot of people ask.
Personally, I don't think there is anything wrong with that, ethically. However, sometimes deworming when it isn't necessary can do more harm than good.
I often recommend more natural products such as parazap.
Was going to worm my babies because there is no way in my immediate future of getting a fecal to the vet (I work 6am to 7pm). My oldest, 5 months, was a petsmart baby (healthy but smelly poops) and he is almost 300 grams. My baby, 3 months, is 80 grams.