Just because something is possible, it doesn't make it reasonable... or probable. If you're in a ranked game, the intent is for the match to be competitive, revolving around the ruleset Riot has laid out (5v5). Sure, some people are just there for kicks and a 4v5 might be "more challenging" to them and thus "more fun," but the fact is, a 4v5 isn't what most competitive players want to see. As it is now, voting to remake the game doesn't cost anyone LP except the one who afked/DCed, so why even permit a 4v5 to take place? An auto-remake could be annoying for those that are in higher divisions with unusually long queue times etc, but for the majority of us, that isn't an issue. Even with long queue times, I'm not sure many would want to risk a loss in a 4v5.