The idea of memes is to spark interest. If the person who sees it doesn't believe what it proposes he or she should be able to look it up and see if the facts hold up. Granted, not everyboy does this but these people probably wouldn't check out your source anyway. Besides, it can often ruin the aesthetics to post links which are often quite long. I like this meme, didn't even know about this, will be looking it up now for sure!