I was told to do it in exchange for money

and most of the time neither do the business folk

Allowing libraries to accrue over generations is something business folk keenly care about because it impacts profits over time.

It's literally why they have rules against transferring ownership.

You can tell yourself it's for other reasons, but you'd just be lying to yourself about Valve being more benevolent than they actually are. They actually are in it to make money. Being told to do it in exchange for money is pretty much why this will happen.

Valve, at the end of the day, is still a company even if they're marginally more consumer friendly than most. (Let's not ignore that a lot of their "consumer friendly" decisions, like being able to return games, were literally because of laws saying they had to. They didn't do it out of the "goodness of their hearts," they did it because in some places they were being legally required to do so.)