If you think Darius is strong, wait till you fight a Fiora.

Both have unstoppable ults. If you can't outduel someone, you usually push. Both run Hydra, which makes them both intrinsically decent pushers and makes it hard to deal with them by pushing as well.

Now let's pick Fiora over Darius.

You lose a really low range pull that leads to a small heal if it lands, but gain evasive dashes and attack speed. Your true damage is no longer tied to your ult, but is still is at a gamebreaking amount and forces your opponent to endlessly reposition (amazing for torturing people). Your heal is weaker if you have incredibly low life, but is otherwise far stronger. You have AP ratios, so you can actually build AP and not be completely useless. You're much sexier. You're slightly faster. No one realizes how strong you are because everyone is busy bandwagoning and banning Darius.