How to make a fair and balanced game.
You don't! You reward incompetence, and make the literal easiest champs the strongest by far, and give them every tool they'd ever need, while making the hardest champs the most pathetic because whales can't play them.
ADCs? They do nothing but right click, but have the most damage, the most sustain, the highest item diversity, the least drawback / risk, no counterplay, the highest range (outside of edge cases), and all that.
But then, someone like Ori, or the new Kat, or Taliyah, or Ivern? Very low item diversity, low damage unless you do everything PERFECT (still, even when done perfect, an ADC triples your damage), highly telegraphed and lots of counterplay, overall short range, lots of risk, very low sustain if any, and so on.
Now, doesn't that seem a bit backwards? Shouldn't the easy champ be, you know, weaker? If played at the highest potential, the harder champ should be dramatically stronger. But no, in today's backwards ass society, EVERYBODY WINS! ... that, and whales can't play the hard champs, so they can't be strong, otherwise the whales would feel bad and might quit! Can't think about anything but money! Nope!
Sure do have to love F2P cash grabs, and today's idiotic society. Sure would be nice if Riot gave a fuck outside of income potential -- but, that's just not how things work anymore.