Why would selling debt make you morally not responsible for it? My mortgage has been sold multiple times. IMO, I still 100% have a moral (and obviously legal) obligation to pay it.
Unlike secured loans like mortgages, the cost of default for unsecured loans is already priced in to the interest rate of the debt. Once it gets sold a third party, that's just a bet by that company that they can strong arm you into paying them something above what they paid for it by exploiting your anxiety or misplaced sense of duty. They didn't earn anything -- they didn't create a service or good that you found valuable, didn't invent something that saves you time, didn't make you life easier or more comfortable. They are scavengers. There is no moral obligation to enrich scavengers.
> Unlike secured loans like mortgages, the cost of default for unsecured loans is already priced in to the interest rate of the debt.
That cost likely also takes into account the money they can get for selling the debt of defaulters. Otherwise the bank down the street that does this more accurate calculation would be able to undercut them by offering a lower rate and take all their business. There's no free lunches.
The existence of a secondary market for debt affects the price of primary issuance of debt (in a way that benefits borrowers).
Your argument could be applied equally to say that anyone who buys a share of stock in the open market (not during an IPO or secondary offering) hasn't actually made an investment in the company because the company didn't get those exact dollars.