Everytime somebody does a bit of good, he is more severely judged and on highter expectations than those doing nothing. Generally by people not doing much themself.
In the field of ethics, this is known as the Copenhagen interpretation of ethics [0].
In short: "The Copenhagen Interpretation of Ethics says that when you observe or interact with a problem in any way, you can be blamed for it. At the very least, you are to blame for not doing more."
Be careful with this line of thinking. Not everyone contributing something is "doing a bit of good"; it's quite possible they're making it worse. It's sorta like "good samaritans" who try to help accident victims, but because they have no training, end up hurting the victim even more than if they had just left them alone until someone qualified could get there.
Just because someone (or some group) contributes something to the Linux ecosystem doesn't necessarily mean it's a net positive. It could, arguably, be a negative: it could cause more fragmentation and confusion, it could make Linux look bad to outsiders (decreasing adoption rates), it could take mindshare away from a better organized project, etc. Worst case, it could be done with malicious intentions, such as contributing code that has a secret (and not obvious) backdoor/vulnerability.
Also, I think there's a logical fallacy about criticizing people who don't contribute yet offer criticism, though I can't name it. For an extreme case, imagine a group of lousy coders writing an OS kernel, and some actual kernel expert like Linus or Dave Cutler jumps in an offers some criticism, though they aren't contributing to this particular project. Who should you listen to, the actual expert in the field, or one of the amateurs who really doesn't know what he's doing? Obviously, the expert's criticism should be considered and not rejected out-of-hand just because they're not a contributor.
Wait, what? Valve has been making huge contributions to the large parts of the Linux ecosystem.
Of course they can do more -- anyone can, but patronizing them with "be genuine" and "follow the shiny thing" is really unnecessary.