Leaver Buster system

I'm here to report a situation that happened to me recently and that it has bothered me for a while (as well as other players as far as I'm concerned) that is the fact that people who stay in base, trolling, don't get banned or restricted. The thing here is that the leaver buster system doesn't automatically restrict players who stay in base moving every 1 minute and placing wards everywhere. I don't know how Riot's system works for these cases but I don't think it is that easy to detect cases of players that do this on purpouse in the middle of so many reports of other people. In my case, some 2 premades got mad and harassed the heck out of the rest of the team, leading to our defeat. Here's a video if you even bother: https://youtu.be/hzMhNwX-Qjg

Anyway, I'd like to hear more about how these cases are dealt with and hope you can give me some feedback.