Most balance problems come from Effort/Reward distribution between roles

A simple question, does more effort equal more rewards? And should League be balanced around it?

Mid is the most demanding role in the game, with squishy and often highly mechanical champions, six or more directions enemies can come from and basically asks one to dominate the whole map to carry the game. As such, best midlaner = best player gave us 'gods' like Faker and Apdo. It also caused half the players to main midlane.

Top and Jungle allow for much more roles, and as such can be very forgiving for Garen and Udyr, but can take skill equal to mid on others. Toplane is still the most vulnerable location in the game, pits you into 'impossible' matchus like Pantheon and Teemo and has the least comeback potencial in the game. Jungle is extremely variable, and has a lot of people picking stuff like Udyr and Xin and just running at you. On the other hand, stuff like Lee and Nidalee can put some insane map pressure if the player is good enough, to the point where they are permabaned in high elo whenever they're half-decent.

Bot is ultimately the easiest place in the game, as you can always scale up and the ganks will never be too unfair (compare a 1v2 top to 2v3 bot). Adc can always scale up and rely on allies to keep them alive, but most of all they aren't pressured to win and can simply farm. Supports tie in here, as they can just sit back and relax, reacting only if the carry is in danger. What's funny though, is that people react really badly to some of the more skill based champs in botlane. Kalista and Thresh were supposed to be strong in the hands of good players, as they needed good mechanics and Kalista relied on actually winning the lane, rather than just farming for 15 minutes. This led to everyone calling them 'cancer', which led to nerfs, which led to getting oneshot by a Twitch with Lulu shields and no counterplay.

So no, bot lane is not 40% of the team or 50% of laners looking at skill alone, though they could have been. Does more effort equal more rewards? Well seems like it does not.