When I first started playing this game I assumed that people picked champions for their play style, and winning a game would be because one team is more skilled than the other. However, I've noticed things with champions being better late game than others, some having better poke that lets them win lane, etc. and that doesn't really seem like "balance" to me. Why is it like this compared to skill being the only winning factor?
TehNACHO3 votesDifferences in kind.
This actually has a lot more to do with "champions for their play style, and winning a game would be because one team is more skilled than the other." than you're probably giving it credit for. Certain champions for example have entirely different power spikes. In a game between a 
and a 
, Graves' power spike comes waaaayyy earlier than Jinx's for example, and it would be essentially part of his play style as a champion to win lane against Jinx if his player is using Graves competently. On the other hand, it's part of Jinx's play style to hyper scale into the late game as she accumulates more gold, so by the end of the game, even if Graves was winning earlier, Jinx can and probably will catch up to and surpass Graves if the game lasted long enough.
This has everything to do with skill, just in a different way than you're probably thinking. You're thinking chess-styled skill/balance, where everything is on equal terms with each other. There's nothing wrong with this kind of thinking, don't get me wrong, but you have to realize there are other ways to achieve balance. It's why Ranked games has such an emphasis on the pick and ban phase; it's part of a player's skill to recognize what their champions do best, what the opponent's champions do best, and how to play with or around it. It's part of why some champions have much better poke but other champions are damn near guaranteed to win straight up 1v1 fights. It's part of why some champions have amazing AOE Effects and others focus on nuking a single person down. It's part of everything that makes an Assassin Carry different from a DPS Carry. Every champion in the game (well, almost every) has a very unique role and job to fill that only they do, and it's part of a player's skill and part of overall game balance to play with or around their strengths and weaknesses.
Lord Dusteon1 votesBecause it provides reasons to use different champions and differentiates champions? Pantheon is going to be great at picking out single targets and being an early game bully, but both of those are less useful lategame, so he falls off. Vayne has amazing DPS, but she can't fight well early and needs several items to be effective, making her great lategame.
Making every game based entirely on 'skill' would necessitate homogenizing the entire game, which would make it pretty boring.
Teridax681 votesPower curves do involve skill, though, even if it doesn't directly translate to just landing abilities and the like. 
has an incredibly powerful late game, but has to work hard to get there, and can get shut down earlier on. 
is another champion whose powerful late game is countered by a weak early game, and who can also get forced back via ganks and aggressive plays. Knowing a champion's power progression throughout the game and exploiting it is one of the key components of gameplay, which is why letting, say, 
farm for free throughout the game, or 
roam, is a mistake you learn over time not to make.
Even so, though, moment-to-moment plays are key to determining the outcome to any fight, even when factoring power curves. Assuming neither side has an overwhelming lead over the other, even a 
can win against a late-game, and champions retain key weaknesses even when they're ahead ( , for example, has extremely low mobility, and so can always be kited regardless of how fed he is). Skill is the determining factor in games, except it applies to more subtle and long-term aspects of it alongside shorter-term plays and outplays.
Epilogue of Life1 votesBecause there are champions made to be lane bullies who fall behind despite small edges as the game progresses.
