Someone who bought an 8hr game then thoroughly enjoys 8hr game and resells it to a future customer is a loss for the creator. The creator does not make money from the resale, the customer himself does not get a full refund and Steam loses future indie games on it's platform. It's a loss for everyone and a symptom of the dying games industry. Making big $$ in games was a 2015 thing, it's getting all locked up from here on out.
Then I went to the Steam Communitu hub and the first thing I saw was a thread about someone debating refunding the game. He finished the game (not easy to do, the puzzles require considerable mental effort) and enjoyed it, but felt that Steams "2 hours of playtime" refund policy laid a moral framework by which any game that provides less than 120 minutes of entertainment is a rip-off and should be refunded.
This game was a solo-effort that took 5 years.
Just as big businessed are cut-throat about screwing over consumers in the name of "shareholder rights", people are often equally cut-throat about screwing over who they buy from in the name of "consumer rights". Remember how many people abused Costcos return policy back when it was ridiculously generous?
If my indie favorites like Celeste became refundable or resellable, I wouldn't do it even though I've finished the game and won't play it anymore....this is out of a desire to be a patron to great art. But I think this view is in the minority. Most gamers will maximize their wallets and would return/resell their indie games when finished.
There's a discussion about how long a game should be, and something that 1.5 - 2hr is the same length as a movie. Having grown up on 60hr FF7, 2hrs seems to be blending the art form with film. Changing the refund time to 25% of the runtime makes sense for linear stories, but not so much endless mmo's or whatever.