There is seriously a problem with your game design when one of your stats can be the only damage type on a team and that team still have no trouble in steam rolling a game, but changing that stat to any of the other stats (AP or HP) fails utterly.

On top of that, these primarily AD subclasses are given specific itemization choices (which end up causing problems with other classes constantly because they're very easy to utilize in other AD classes). Classes like Juggernauts, Marksmen, and (AD) Assassins, all get their own items tailored for their subclasses.

Yet the AP divers, AP assassins, and most vanguards and enchanters are made to utilize the same items as all of the mage subclasses (another stupid situation). And the item designs are clearly reflective of this.

While items like (just to name a few) seem to be designed with very little, to no, consideration of cross class usage.

I'm pretty sure this is only because AD stacked games tend to be much shorter, ending with one side stomping. I don't think that riot has a particular preference for AD itself, but chasing this mythical "wider audience" has been undermining so much of the original design which worked so well and made it so competitive and popular.