Banning / Disciplining... instead of that account, why not that ip address and all accounts from it

The affects multiple people in one household playing or even college campuses. If I visit my buddy's house and get banned, all of a sudden he wouldn't be able to play anymore either.

I do agree but don't because someone here pointed out. What happens if it's a college IP. So you punish everyone at the dorm because of one person?

Riot believes in second chances so they will allow them to create another account. I'm sure if it got super bad then they may consider an IP address ban but I would say it would be extremely rare

Apart from the collateral damage others have been pointing out, IP bans are also rather ineffective. I personally wouldn't even have to try to avoid an IP ban, because my router resets once every 24 hours and gives me a new IP adress. Even if you don't care for collateral damage at all and go for a larger scale and start essentially banning entire citys based on IP, there are still ways around that.