Risk vs Reward

Does LoL have a solid risk/reward system in term of champion difficulty/mastery?

Personally, close but no cigar (sorry ) I don't think mastery of higher difficulty champions proportionally reaps the reward. Take for example, I think he is the hardest ADC to master due to many obvious reasons. His style includes many risks. However there are many low ceiling adcs that are easier to master who can do just as good if not better (while being safer, having more control over positioning and clicking less lol). So what's the point of playing and spend much more time/effort (risk) mastering him when you can just play can have a much bigger impact (reward)?

This is probably one reason why higher level play does not have diversity for everyone will pick the lowest risk champions who can reap the highest rewards. Just my thought.