Numbers tend to skew perspective. All I know is that NO game should have a perfect score. Ever. No game is perfect. Ever.

So a 10 point scale starting at 9 and ending at 10 ;)

You're assuming that every website or magazine is reviewing every game ever releases. When in fact they only stick to those with higher standards than the average to begin with. Most publications don't even bother to do a review for all that shovelware that comes out constantly on steam, PSN and Xbox Live, let alone those titles on mobile platforms. If you take those into account, I'm sure the average will drop to 5 quite easily as many of those games deserve a score between 0 and 1.

5 is average of course, a game that is playable and enjoyable, but has equally significant flaws that will turn many off
6 is good if you like the type of game, but eh otherwise
7 is a solid game, but not great
8 is a great, high-quality game
9 is an excellent game with many many good points, but a few annoying flaws
10 is a genre-defining, fully-realised vision, it may have minor flaws, but it is a must-have, unless you have no interest in the genre of game
.
On the other end of the scale,
4 is a game that had a solid vision,and is playable, but has glaring flaws that significantly detract from the experience
3: see 4, but flaws are even more intense
2: A terrible game that has very few redeeming features, most would not go past a few moments with it
1: An unplayable mess that should be avoided at all costs

The issue is, that scores are entirely subjective. A 7 to me might be a 10 to you, and likewise, a 10 to me might be a 6 in your eyes.

To me, 5/6s should be given to games that do what they look like they do, but don't ever feel like they're excellent; for example, Super Mario Maker, Kirby's Return to Dreamland, Mario Sports Mix

I wish people used logic when it comes to rating. To me, antyhing from 0 to 2 is fucking meh, anything from 2 to 4 is... well, they tried. Anything from 4 to 6 is average, it means it can sway either way and there are things to be enjoyed, but they're plagued by serious flaws. Anything from 6 to 8 is more than decent, it means it's not the game of the century, but it's a damn fine game. And anything from 8 to 10 approaches the "MUST BUY" (8 - 9 a must buy if you love the genre, 9 - 10 a must buy/must try not matter what it is, but it's hard to define cause everyone's different but sometimes you just feel it when a game is pure awesomeness) or something similar.

There is numerical average and statistical average (as well as others). The average video-game most likely scores above 50% but that doesn't need to correlate with the definition of what average should be. What I mean by this is say the average video-game nets a 7/10 score, that is now the score that constitutes the industry average score of a video-game which in turn makes any video-game below 7/10 less than the average game thus giving way to 7/10 being portrayed as "average".

It is almost necessary for a reviewer to conform to the industry standard, otherwise the score will be misrepresented, although the review could stand on its own.

Nothign is perfect ever. But I don't knwo why people have the strange thing with putting the top score to perfect. If you have a scale you should utilize it fully, which means the top-score isn't the same as perfect. As simple as that.

5 is an average game. The problem is: an average game is not worth most people's time and money, so the actual average for what people play is 7.5.

Average should be a 7, meaning it is a good game but nothing spectacularly impressive about it. No one should be turned away by this score.

6 should be below average. It is playable, and even fun. Worth the money for those into the style, but below the normal standard of quality.

5 means it is functional, and there is nothing left to see here.

anything below a 5 is broken, and the numbers 1-4 signify just how broken it is.

Now an 8 is above average. These games are what many people should start to consider as heavy hitters.

A nine is a must own game. These games can have their flaws, but they are considered to be overshadowed by several pros that make it a game that should not be skipped.

A 10 is near perfect in the eyes of the reviewer. Nothing is perfect, but this comes damn close.

Unfortunetly this is not how a lot of gamers see these scores. A 7 is considered bad and depending on the IP, an 8 can be seen as a let down. I have seen people skip games because they only got an 8.

At this point I believe the numbered scale is flawed. Read the review and read the list of pros and cons at the bottom. Too many people have different ideas of what each number means for it to work on an effective numbered scale.

Part of the problem is weight, and another is how you use the 10-point scale (are you only going up by 0.5s? if so, why?)

As long as the reviewer is transparent and consistent, you don't have problems. When they close their eyes and toss out numbers arbitrarily, you have Aliens: Colonial Marines scoring a 9/10 or The Last of Us scoring the same as Knack 2