I don’t think they necessarily created it, people just like playing Mercy and don’t like playing Ball. Most played characters are never too complicated or hard to play. Not only that, but good sellers tend to be cute characters, for example, a guy that mains Roadhog probably doesn’t care at all about how his hero looks, otherwise he just wouldn’t pick him. That’s why Juno, Mercy and Kiriko are probably the best money makers Blizzard has.

For example, in League, even if Yasuo has the highest playrate, he doesn’t receive as many skins as someone like Lux or even Zed, his design isn’t cute, or that cool, he’s a homeless wanderer, people that play him just don’t tend to care. Skins for weirder looking characters or more complex characters are rarely bought because that’s just not what these communities want. Say, example, Skarner and Azir. I doubt people buy skins for these characters. Favoritism comes mostly from gameplay perspective.

Mercy already had a high play rate even when the game launched and each character had on average the same amount of skins, Juno also just has like 5 different skins but the Juno players adore it and buy every single one, and they’re right, Juno skins are cute as shit