Below is a video from the community of Heroes of the Storm players, showing funny highlights of gameplay. You'll find similar videos for Hearthstone, and I expect that other games have similar community-sourced highlight reels going around. In each such scene, I find that the community is somewhat healthy and seeking organic growth by demonstrating both how the game can be fun as well as how its interactions sometimes produce absurd situations.
These videos are not only evidence of existing populations large enough to organically create this stuff as an expression of emergent behavior, but also provide the curious an idea of what actual play looks like (and thus what to expect when you play the game). It's the best form of marketing I can imagine, and it's given for free by fans. This is social proof, and no amount of artifice makes up for this expression of engagement by fans.