Playtime can't be guaranteed, unless its a movie you have no control anyway. Its most likely just a suggestion. Did this game suggest a playtime that was vastly different to your experience?
Refunding a cheap (in price) indie game before the 2 hours play mark, AFTER finishing it is just a dick move. Also some games cannot be just measured by its playtime alone. Yes you can for yourself. But that would be like saying "oh I refund all 50 hours games, because I only consider a game to have a value over 60 hours playtime regardless its price".