People bring up a lot of good points about full LP loss prevention being abused. I can definitely see it happening.
If I could change things it would be made to reward good play more than safeguard players against teammates' bad play as you suggested. If your teammate is trolling or minimally contributing towards your win then they gain less LP. If your teammate is pushing objectives, warding, getting good individual scorings (just like how mastery score is determined) then they gain more LP. This would not be determined just by KDA but also objective control, vision, income, etc. Anything that Riot considers when giving mastery scorings really, which are all tailored to specific roles and champions already so it seems to be efficient enough at first glance for this purpose.
Same goes for a loss. If you didn't give up, afk, or troll (aka ghost/cleanse nunu adc w/0 cs at end of game) you lose less LP. If you left the game, had poor contribution, poor warding, etc, you lose more LP. Your teammates that remained composed and kept on as best they could would see varying LP losses depending on their own performance.
For three reasons I think this is beneficial for literally everyone:
- Players performing really well climb faster so they can get to a rank that suits their contributions and performance in games.
- Players being hard-carried climb slower and fall to where they are among their own skill level faster.
- Players who do not try at all are massively 'punishing' themselves. Trolls, inters, griefers, etc.... they all hurt themselves the most.
I think it's time that Riot stopped punishing or rewarding everyone the same amount just because we're on the same team. In Solo/Duo Queue it doesn't make sense for things to work this way to begin with.