I think the probably eventually becomes players trying to use the system to get a replacement player who is better than someone on their team.
For example a person is cs' ing really badly, let's kick him before he falls too far behind and get a decent replacement. Or someone dies a couple times in game and isn't great defensively so they get tower dove and keep dying. Yes they suck but they aren't feeding intentionally. So you kick them hoping for a better defensive player to take their place.
Also, assuming this is available in ranked, how does it work? Let's say X is the worst player on his team and it's overall a close game and then your team gets an ace and pushes to end. The teammates don't like X so they kick him - does X not get a win, does he get a loss or does nothing happen, what if he's in a promo? Does the replacement player get a win for doing nothing? Do replacement players that join Games that are really far behind get a loss when they lose? What if someone legitimately DCs and reconnects after 2 minutes, do you kick the replacement and let them back in?
There are too many problems with this.
I think when it comes to league, what we need is an overhaul on player behavior. Get rid of players who rage quit - it still sucks when someone DCs or needs to leave due to a real emergency, but it's fairly obvious that the guy who's 0-4 in Lane and quits immediately after a death is rage quitting. Even moreso when you look at their match history and every one of their leaves is when they have a bad KDA - they never leave with a good KDA. Rage quitters are the biggest problem with this game (these are often the same players who rage on teammates for sucking) and should be permanently banned once the behavior shows up consistently. The next steps will be to get rid of players with severe trolling, etc.. It's really quite obvious when someone is trolling as opposed to just sucking.
If leavers were the only problem and it was limited to only when people had real emergencies, or real connection issues, the occurrence rate would be sufficiently low that no one would care much. The problem players are those who leave because they don't like how the game is going and those who behave poorly intentionally, and really these players aren't worth "reforming" they should just be eliminated entirely.
Finally, surprise visitors are fine - in general I think people who don't at least call you first are being rude but I mean that's their fault and not the players. Babies napping though? Seriously, if no one else is home to deal with them - babies wake up from naps, it's what they do. Playing in that case is irresponsible. There's a huge difference between your stove Catching Fire (in assuming it's in the oven for hours rather than in a pot on the burner for 30 min) and your baby waking up or something like that. If something happens less than 2-3 times a year, then sure maybe you can try to play. If something happens even every month, don't value your 4 teammates time and effort so little to put them at risk. Babies wake up from naps EVERY NAP, so really if your significant other isn't there to deal with it you probably shouldn't be starting a game of league...