I have posted about this several times and have yet to receive a satisfactory answer.
To sum up my thoughts, I have a solution that would help against people that legitimately disconnected from games (since the client is able to detect that aka a surrender with less than 5 votes) but would NOT help against people that run around is base, field goal, essentially go afk without getting kicked from the game.
My thought is this: loss forgive the other 4 members of the team with the disconnect. Nothing happens to the other team. They didn't have anything to do with the disconnect (if players are ddossing other players, I would have a slightly complicated solution that I can explain in a later post if anyone actually thinks its an issue) and therefore don't need to be apart of any of the "fixes." Just to be clear; my solution isn't to stop dcers, its to help the other 4 players. Having done that, the reason this post gets so long is because I have to also include an anti abuse device; and that is where my explanation gets a little lengthy.
With the four people that didn't do anything wrong and who just had 20+ minutes of their life wasted not also losing LP (or losing a promo game), we can focus on the person dc'ing. My suggestion would be, in addition to the usual punishments given out, have that person take around an additional 60 lp loss. Under the current system, quitting a game that you know you will lose nets the same lp loss and has the added benefit of allowing you to do something more productive with your time. After all, if I can go make lunch and lose 20 lp or just lose 20 lp, I'm more likely to go make lunch and lose the lp. Yes, that is a rather silly example, but it illustrates the point that there is no incentive, besides the threat of a ban, to not afk. And since riot is kinda forgiving about disconnects (at least infrequent ones; a viewpoint I actually support), quitting a game can be viewed as a better option for people once in while.
Attaching a large lp penalty for disconnecting from a game will actually make people stay in games that they will likely have quit before, because instead of losing one games worth of ip, they lose between 3-5 games worth. Now they have a reason to stay in the game instead of going to make lunch. (But still go make lunch after the game if you are hungry). This also makes it so that people that are still willing to try to abuse this system can ONLY do so in bronze/silver and even then, can only do it infrequently (since
"But what if something happened outside of their control and it wasn't a rage quit?" Okay well there isn't really an easy way to say this so I'll just say it: tough luck. The way I see it, there are acceptable reasons to disconnect, and unacceptable ones. In the case of acceptable reasons to disconnect, I would argue that the person wouldn't care about the extra 60 lp loss. Therefore, when I talk about acceptable reasons, I'm talking about hospital visits, car accidents on your property, home invasions....etc. If any of these things happened to me, and I disconnected from a game as a result, i wouldn't be concerned with the LP loss. Also, hopefully, things like this aren't a regular thing in your life, so disconnected ONE TIME won't be a big deal. Other reasons, like not leaving enough time to finish a game, rage quit, etc deserve the lp loss anyway. And above all, the most important thing to remember is that if this isn't happening often, then it really isn't a big deal. If you are disconnecting often, this will affect you a lot, but then maybe you shouldn't be playing ranked anyway.