That's quite an exaggeration. The other riders always get painted unfairly, and from what i've read all throughout the internet, whenever they provide reasons for their struggles, they label it as an excuse. Then they act as if Vale is always gracious in defeat and NEVER makes excuses.
Again if you flip the script and Lorenzo had done what Vale had done in the Sepang press conference, he would be crucified right now and would be considered the biggest moaner in MotoGP ever. I can guarantee you the fans wouldn't even give it a second thought to look at the facts (like what they did with Vale). There's no swaying a die hard Valentino fan because all objectivity goes out the window for them.
One of the most ironic things this year is when Jorge was getting thrashed earlier this season for running away with the races. He was labelled a coward for not wanting to engage and fans were even begging for him to slow down so he can scrap it out with Vale. At the same time, Marquez was being praised by these same fans for providing epic battles with Vale, and that this is how Motogp should be. Then next moment he's labelled as the villain who prevented Rossi from winning his 10th title. hahaha So at what point was supposed to stop? Hypocrisy is rampant amongst his fans.
I don't know if this has been posted but this article explains it very well.
http://trunkman.co.uk/blog/doctored-motogps-obsession-with-valentino-rossi/
Fantastic write-up! David Emmett is by far my favourite moto journalist. He pretty much summarized what's in my head.