It still is abused for short indie games, with people buying them with the intention of speed-running through and refunding.
The refund policy is intended more for “crashed repeatedly”, “far too slow despite my machine matching the stated specs”, and “simply wouldn't run”, type problems, rather than not liking the game. There isn't much a service like Steam can do about that, that won't be abused, other than offer demos (enough for you to try out those core mechanics) which is really down to the game creators and out of their power. Other than that you just have to not be first in line, and wait for reviews from sources you trust.
Too much shovelware on Steam these days, and the user has to pay retail price to even try it.
The current limits are 14 days since-purchase as long as you've played the game for less than 2 hours.
Costco has a no-questions-asked return policy, and demo-ing your purchase is absolutely part of the expectation for how people will use said policy. Steam even explicitly includes "it wasn't fun" as a valid return option, as long as you reached that conclusion quickly enough.
To be clear, I'm not saying the policy is wrong, it's clearly designed to prevent abuse, I'm just saying that it's not no-questions-asked.
https://bestlifeonline.com/costcos-return-policy-membership-...
You sound like the type of person who has a problem with Dropbox offering unlimited storage and then reneging when people upload 17 petabytes of anime.
Valve is there to facilitate the sale of the game, not guarantee the game is good.
In general their policy very good, but it's not quite no questions asked—they're pretty strict about the 2 hour playtime limit, which is quite a short time to decide if a game will actually be fun. In many types of games by the time you get through the tutorial and have access to all the game mechanics you're already past the two hour mark, and they also can't tell the difference between actual play time and time in the menu while you're doing something else.
EDIT: To be clear, I'm not saying it's a bad policy, there are obviously reasons for this. But it's not truly no questions asked.