It's one of those things that can't really be implemented because of the abuse cases. If things are going poorly, harass teammates in the hopes one (or more) will leave and 'take the fall' so the others can get reduced LP loss, which would be no bueno.
AFKs suck, but statistically you're more likely to play against a team with an AFK than play on one (4 potential afks on your team assuming you never AFK, 5 on theirs), so while it feels really bad when its on your side, and especially when they're in a row, in the long run you're probably going even in LP or even gaining due to AFKs, so have try to faith in statistics when the rough periods happen.