And it’s not like the parents would actually kick them out if the missed a month’s rent.
You will NEVER build your credit for the times when you need it (buying house, unforeseen circumstances, a car that costs more than $15k, and I’m not being an asshole, just using that as an example) if you do not have some line of credit such as a personal or car loan, credit card, etc. A bank can not accurately gauge your credit if you have no credit history. Having decent income with no debt will only get you so far.
most normal people have car payments. Not everybody has $15-40k (normal range of a new/er car most members here own) cash to go out and buy a car these days and/or want to drive a 20 year old shitbox.
I had a few vehicles without payments in my lifetime but then I decided I wanted something halfway decent that I couldnt afford to pay cash for.