With the latest 1BE scandel, sure Riot messed up on it but that goes for any bug or mistake, you can't simply ignore it.
You can't tell a playerbase not to use exploits within the game but also let thousands of players get away with not paying for hundreds of skin, orange essence and gems.
"but this doesn't negatively effect other players"
What about long time supporters of the game then? could you imagine spending hundreds upon thousands of euros on the game only to be told some people managed to abuse a mistake riot made to gain the same money's worth of content for free, and that Riot hasn't done anything to correct this?
You'd probably feel pretty stupid about yourself for supporting the company for so long, spending so much money and if anything, you'll probably feel encouraged to abuse bugs now because Riot is clearly fine with some abuse of the system.