There are a LOT of idiots and complainers in the world, but having a hard time gaining muscle does not correlate with that. Being a complainer is being a complainer. If you're a complainer and you have a hard time putting on muscle, you'll likely complain about being a hardgainer. But if you aren't a complainer and you have a hard time putting on muscle, you likely won't complain about it, but you'll still be a hardgainer.
Simple understanding, and moreover, stating that you are a hardgainer is not a complaint.
I would say that a good majority of those who put on muscle easily also use unnecessary supplements and also have no idea what they're doing. Yet they succeed at putting on muscle where others in the same boat fail.
Not knowing what you're doing has nothing to do with one's natural genetics. Sure, knowledge is part of the solution. But the question is whethere the hardgainers are hardgainers or not. I think a lot are not. But I also argue that a lot more are than some people are willing to accept. And they may, simply, need more education...but that doesn't change whether or not they are hardgainers.
Take BTB. He was able to overcome by eating and lifting right. Does that mean he isn't and/or wasn't a hardgainer? Does that mean it was or wasn't, on a relative scale, harder for him? The fact that he overcame doesn't answer the question as to how hard or easy it was.
It's easy to just say "get over it," "push past it," etc... And, ultimately, that is true. Whatever challenge we have in life it's the same. Maybe a person's dumb. Maybe they're disabled. Maybe they have a stomach disorder. Still, they have to move past that obstacle if they want to succeed. But it doesn't change the reality that it is significantly harder for some than others.
And a total lack of understanding or compassion for hardgainers won't help them any more than the pantry of creatine.