Multiple Accounts is an Issue that Needs to be Addressed (solution proposed)

Premise: toxic players just make new accounts so they can continue to play even if their account gets banned.

Example: Last night I played a game with 3 friends, our fifth player, given to us by matchmaking, was a Jinx. One of my friends played Kennen support, and did not do well. The Jinx player became upset because Kennen was feeding, and became increasingly toxic and defeatist. They trash talked and tried to surrender at 20. When the rest of the team voted no, they afk'd at fountain and just harassed us in chat for the rest of the game. I tried to point out that they would have more fun if they were getting kills and fighting in teamfights (we were doing quite a good job holding out 4v5, and with Jinx we would have stood a very good chance of a comeback). When Jinx responded with more harassment, I asked them to stop harassing us and that we would report them.

They responded with, "I don't care, I have 4 accounts."

If we want to improve the player experience we ought to stop toxic players from being able to just continue playing on a different account. Players can completely circumvent the reform system by creating extra accounts.

Proposed solution: Block MAC or IP addresses associated with banned accounts.

In layman's terms: Every device which communicates over the internet us required to have a unique identifier which is stored on the device and cannot be changed. This tag is used to identify the device during communications, a lot like IP addresses. My suggestion is that RIOT implements bans to affect devices, not just accounts.

It should be possible to program the League of Legends servers to check login requests against a blacklist which could be comprised of all the MAC addresses of banned accounts' most recent devices (either their computers or even their network routers and switches). If the servers reject any computer (or any computer on a router's network) that a banned account has used (for the duration of that ban) then that player would not be able to re-enter matches and continue to impact other players' game experience.

These are my thoughts on the issue, I won't claim to know everything, or be the best at anything. I just love League and want it to remain fun for all of us to enjoy. What are your thoughts on the issue?

EDITS:

1: I am aware that college networks could be an issue for locking out all devices on a router, so obviously to implement this under those circumstances it would need to block only the computer's MAC addresses, and not the network devices.

2: I am also aware that there are some ways around MAC address blocking, but since they are complicated and rather difficult / memory intensive I believe that this would still work to prevent the majority of the player-base from taking advantage of multiple accounts.