Solo Q in a nutshell
Solo Q in a nutshell, in my opinion doesn't actually represent an individual players skill whatsoever. I can break it down into three simple reasons as to why solo Q does not represent what it claims to, Moreover is the cause for the toxic attitude most of the community is experiencing.
KDA - Lets be honest here this is a 5v5 game and if anyone told me they carried 100% of their games to achieve the rank they currently have I would know they are an egocentric "try hard" at best. Yes, you can heavily influence a game, however does your win - loss truly display your capability or "skill" I would heavily argue no, it does not. KDA should be considered when awarding players in solo Q LP.
No promotional gain from teamwork - For a game that is actually a 5v5 game meaning you need to work as a team to succeed solo Q seems very out of place. Random players are all selected of "similar skill" to fight, however there is no incentive for players to care at all about their teammates or their well being, other that if the game results in a win. I believe if players were instead rewarded for good teamwork such as positive KDA or being awarded teamwork votes, they should also then receive some sort of LP reward for doing what is best for the team and community, regardless of win or loss.
Lack of sever rank reduction for "bad games" - Finally, I also believe that players with severely sub par performance (negative KDA) should be severely dropped in rank depending on the severity of their "bad game" (Negative KDA). After all this is a team game, and a player with a score of 0/10/2 is being a very poor teammate in the very best of circumstances. Also if a player are truly having a " bad game" too such a caliber (Negative 8) then perhaps you are not in the correct elo for your capability. This lack of punishment allows players to intentionally "throw", "troll", "feed", or just not try at all in a game with no more repercussion than any other loss, whilst severely impacting their teammates which is not something that a team game should be promoting.