Is "unfun to play against" a legitimate reason to ban champions?

I've already asked in the past why people continue to ban Vladimir and Zed. Most of time the majority of answers I receive are "they are unfun to play against". And then I ask, is being "unfun to play against" an actual, legitimate reason to ban champions? I ask that because just because a champion is unfun to play against, does not mean this champion is actually strong. Just look at Teemo, he is one of the most unfun champions to face, but he is far from being one of the strongest champions.

There are a few times where this can be a legitimate reason to ban a champion though. For example, if it is not a ranked game, where victory does not matter that much, and fun is more important, then banning a champion that is unfun to play against will make your game more fun, thus this is a legitimate reason to ban that champion. Another example: if you are really sure that you or your teammates will tilt if they are facing that particular champion, then maybe banning that champion will be a good choice. After all, playing a game while tilted may significantly decrease your chance of winning.

Is being unfun to play against a legitimate reason to ban a champion, even if that means risking leaving open a champion that is actually strong and can actually ruin your chances of winning? (assuming the enemy that picks him is good with that champion)