Because there is no factor most of the time other than the amount of money that changes hands. That is the truth with ICO rating. There was a time when the ratings that are released by these ICO rating websites are more or less reflecting the real deal of the projects. But then it gradually transformed into a money-making machine that will allow ICOs to bid for the number of stars, the highest spot, or the highest grade.
For me personally I will not look on the ratings given by any ICO rating sites since they can be paid just to give a high ratings to certain ICO company who want to list.
And there are so many scams before even by now who get a high ratings so best to check the whole transparency of the project before going on it or much better not to look on them anymore since they are all the same and we cannot pick on which of them is best right now.
Honestly, the ICO rating sites are now becoming the same scams as the projects they are giving high ratings to. No need to bring in the ratings ICO projects got from these sites into your decision factors. It will not help you kept away from possibly investing into a scam project.
If possible, do not invest in ICOs anymore. It seems the best crypto projects out there do not have to undergo this fund raising scheme anymore.