However, this does seldom translate directly into public matchmaking games, unless you're running five-stacks or playing -cm. People pick what they want to play, often disregarding the opposing team and the own team. People stay in lane when they more optimally could gank. You can see a nice graph over here, where you can see that Alchemist is currently the hero that wins the least amount of games, paired with his low number of games played (which is obviously skewed due to certain heroes being around for longer). This doesn't mean that Alchemist is useless, or will lose your team the game. It might, but it doesn't mean that a Crystal Maiden/Lina/Alchemist isn't one hell of a trilane. As the hero pool grows larger, some strats will be easier to counter against (and harder to ban for). That's just how DotA works, with it being sort of ever-evolving.
Some heroes (Lycan, Ursa) take a lot of coordination and effort to stop. This makes him very powerful in public matchmaking games, where there usually is a shortage of communication and coordination. This doesn't neccersarily carry over to the professional scene. I would still want to argue that DotA2 is more balanced than its competitors.
But hey, that's just my opinion, you can find people contradicting every point I made everywhere.