"Nothing is at stake"
Do you fucking know how many games that mentality lost?
"It's just normal, I don't need to try hard" - 0-2-0 Rammus at 20 mins.
You can't learn too many match-ups in normal games because of that bull mentality. Normals are full of people who either try to learn new champs (So nothing to learn from winning that match-up) or players with that bull mentality (So again, nothing to learn from that match-up) or the Zed/Lee/Yasuo mains who pick their best champ and play the match like it's a win or die situation.
I legit never saw Orianna, Corky, Malzahar or A-Sol in normals unless it was me or a friend trying them out, but I see them (except A-Sol, but even he shows his tail once in a while) in ranked games.
I have a hard time dealing with Orianna, but I never see her in normals so I can't practice that match-up there, yet by your logic I should ban her because otherwise I gimp my team, so I wouldn't be able to practice the match-up there either.
The problem is exactly that "no need to try, it's just a normal game" which is why people ban none. If they could freely practice that match-up in normals instead of either getting a free win or a free loss, depending on which side gets the more monkeys with that bull mentality, no-one would ban "none", or at least, a lot less people would do it. But you can't practice in normals unless said match-up is vs Zed or Yasuo.
So fix that trash mentality first then you will see less people not choosing a ban.