First off, you say that the person you talked to when contesting your ban said to create another account. I find this suspicious and so request you provide a screenshot of the chat to prove they actually said that.
Second off, due to the nature of free to play games there's not much Riot can do to stop people from making new accounts without causing collateral damage in the process. Ideally they'd like permabanned players to not make new accounts, but there's no real way to stop them from doing so.
To quote Kei143:
When Riot permabans someone, their philosophy is "the chances of this guy reforming isn't a whole lot, we'd rather not have him in the game". Thus in their eyes, they have already written off the toxic player as a paying client.
From a business standpoint, do they want to remove the toxic guy who has spent $500 but is causing a negative environment for 4-9 other players in every game? Those non-toxics are also spending $500 and probably will spend more, promote the game more when they are enjoying the game AND they won't cause a negative environment.
I personally think it is a fine argument to protect the ones that are paying money and aren't toxic rather than protecting the ones that may pay the same amount but are toxic.
From Riot Tantram, aka the guy who wrote the entire system:
We perma-ban players that we no longer want playing League of Legends, because they hurt the community. We do not want them to make new accounts. We cannot STOP people from making new accounts though.
From Ulanopo's Knowledge Base:
Riot bans people because they make money off of forcing people to create new accounts and repurchase the skins.
Just stop. This is a really silly argument. I didn’t pay for my account any more than you did and while I have bought a number of things, I didn’t have to. There’s nothing relevant to competitive play that I couldn’t have bought with IP.
Also, Riot actively discourages people from making new accounts.
From Lyte: (link (http://forums.na.leagueoflegends.com/board/showthread.php?p=33432435#post33432435))
Actually, if we're permabanning you we don't want your money or your time. Just find another game.
(Help from MadmanWithBox)
To quote Umbral Regent:
If you got your main account permanently banned, the only way you can prove your reform is to not get any further accounts banned.
Riot isn't going to give you infinite chances, they have to put their foot down somewhere - and that somewhere happens to be after the 14-day ban. If you can't be bothered to listen to three separate warnings at the very least, then, why should your main account be given a fourth try? You've already proven three separate times that you don't care about the rules.
My opinion is that if you're worth getting your account back, you wouldn't have gotten it banned in the first place.