Trolls and AFKs

You would think that after what, 6 years, this game would have some kind of mechanism to deal with trolls and afks efficiently and fairly.

I just played a game where a guy picked Rammus. He rushed at the enemy every time he spawned and then teleported to them to die again when he could. It was obvious and everyone knew it. The frustrating thing is you can't do anything about it. You just have to wait 20 minutes. Then at 20 minutes someone didn't want to surrender so we ended up playing 28 minutes. That's 28 minutes of time that 10 people had to waste because someone wished to abuse a system that has absolutely no mechanism to prevent this abuse. To top it all off, I ended up losing 22LP for it.

What's the point of coming out with the new champs and fixing bugs when this blatant flaw in the system continues to exist with no change whatsoever? Makes absolutely no sense. Its the reason why I don't play this game regularly anymore. What's the point when you try so hard to advance and that can all be wiped out if just one person afks or trolls?

His score at the end was 1 kill and 39 deaths. If this obvious troll score is then collaborated with reports why not just perma ban this idiot right away? Why does Riot not do something about this? I just don't get it. This is so frustrating. At least use the personal score system to alter the amount of LP lost and gained based on the performance. This way someone who trolled like this would drop a whole tier down right away and if it keeps happening say 3 times in a row he is permabanned because shouldn't it be blatantly obvious by then?? Also, if it's obvious 5 minutes in that you have a troll on your team then why not allow a quick surrender option with low LP loss equivalent to say a dodge? Why must we wait the full 20 minutes and then lose a heavy amount of LP like 22?