I agree with your points but not the conclusion you draw. To me, the "infuriating, mentally painful or completely unacceptable" fail as games and should all be lumped to the lowest possible score. There are too many bad games out there and to try to make room for all of them on a /10 scale of badness just isn't tenable.heh, I guess that's a clear point of disagreement then as I just used NFS as an example in this thread as to why I feel the scoring range is appropriate. It still has its enjoyable parts despite all the mess, and it's more than technically competent. There's no good reason to give that less than 2 stars.
It's not the full story but I do think an emotional barometer really helps make more sense of this. A 10 is something absolutely enthralling, an amazing amount of fun, something you'll never forget. The games on the low end of the scale on the opposite side of that aren't just "not fun," they're infuriating, mentally painful, or completely unacceptable in every aspect. Then the 5 in the middle is either a weird mix of both sides or something so flat that you don't have any emotion either way.
And yeah, I'm going to go back to "you don't know how bad games can get" every time because I have had to suffer through and review those games. There are many, many racing games worse than Need for Speed Payback.
If a game fails in any of the fundamental aspects of making a remotely enjoyable experience, whether thats currently considered a 5/10 or a 1/10 is functionally meaningless in today's scene.