Double LP for 4v5

Triple for 3v5

I recently lost 26 LP because due to very toxic players being on my team. I just won a 4v5 with great teamwork and gained 14 LP. Where is the justice?

I can see an issue - players duoing and "dcing" half way through a match for high LP gains. That shouldn't work. However, if a champ is at the fountain level 1 when you win there should be some bonus.