Unacceptable behavior goes unchecked

Greetings, fellow gamers. I got into a low elo ranked game with an anivia player who simply wanted to grief the team for fun at the cost of enjoyment for others. Instead of staying in mid lane, she kept going to another lane, leaving mid undefended. She followed me around the map while I was testing to see how she would respond if I left my lane to defend mid. She also used her wall to prevent me from recalling. It went on like this for 20 minutes until the enemy was at the nexus and we surrendered.

Here is the conversation I had with the player after the game. What are your thoughts? What can be done in this community to make it less appealing for people to behave like this? Anything?

Nirgali joined the lobby Player joined the lobby Player: I knew i left a good impression Nirgali: can I ask you a serious question? Player: Let's go Nirgali: I want a serious answer Player: What'cha got Nirgali: are you willing to answer straight? Player: Sure Nirgali: why did you behave that way? Nirgali: what was the motivation for not playing seriously? Player: Real talk Player: Because, to me, it is more fun that playing the game in it's original format Nirgali: I'm trying to understand, you have four other people counting on you to win a game of ranked Player: It is a game Player: Games are meant to be fun Player: So I turn it fun Player: For me Player: That doesn't mean that it is fun for the others Nirgali: at the cost of everyone else? Player: But I'm just 1 game outta thousands Player: They'll live Player: Yea Player: Problem is, even talking to you, I'll get by with it Nirgali: well, that is interesting Player: I have not been banned and been at this for years Nirgali: that you find this behavior socially acceptable Player: And if i am Player: Just another account Player: I do Player: Straight enough for you? Nirgali: yes, thank you for being honest Player: np have fun Player left the lobby