@Take_Opal: While what you say is mostly true, you are completely missing the difference between a 10/10 and a 5/5.
With a 5 point review scale, there is almost no room for comparing separate games. The reviewer decided how good a game is based on its own qualities. Game A is better then Game B, both get a 5/5
Now lets consider a 10 point review scale. With this, a reviewer will decide the score based on previous games he has played. Game A is better then Game B, A gets 10 and B gets 9.
A 5/5 insinuates that a game is good and worth checking out.
A 10/10 insinuates that a game is one of the best games currently available and should 100% be owned by anyone who takes games seriously.