Valve should do something about this. Devs shouldn't be able to do this without contacting Steam first and having a good reason. Especially after 5 years.
I, as a player, can only refund a game if I played it for less than 2 hours and 2 weeks haven't passed. Devs can apparently refund hundreds of copies at once after 5 years without even having to pay you back.
Steam discussion about this: https://steamcommunity.com/app/724090/discussions/0/4415298540308486736/
Posted by Psycho345