It sounds as if someone missed the development of disposable diapers.
Babies grow so fast in the first year that it’s not unusual for a set of clothes to be worn once, or not at all.
A coworker once was bragging that she picked up three outfits for her (toddler-aged) daughter for "a little less than $100".
I didn't have the heart to tell her that my wife had just finished completely outfitting our kids for the fall/winter - including winter coats - for less than that.
I dunno if I'd buy 'gently used' onesies or cloth diapers or such. But clothes, shoes, boots, coats, etc? So long as they're clean and look ok, jeez, why not? A fair percentage of what my wife gets at consignment sales still has the tags in it, too.