A quick question (I'm new to game and that weird ranked system)

So let's clear things here, i started playing league on April of 2017 and i was enjoying the game so far ofcourse i had my ups and downs with understand the champs, game basic and such on. Anyway i started to play ranked around August and ended up at s2 if i remember right.

And now after the new preseason and all the change they made, i want to ask a quick question a game mode called Solo/Duo keep judge your performance of a whole team ? Like honestly the system say "Solo" yet if i get S and my team is feeding monster that rekt me and cost me the game while everyone of them got a D or C+, they lose the same amount of ip as i'm assuming they having the same mmr like me.

Like why ? And don't tell me it about solo carry, you can't solo carry anything when there is lane losing hard that enemy is at our base tower. You know why i keep banneding nasus ? Cause if i play him my team feed and give me no time to farm and if my enemy got it my team will die easily and i would have to leave lane to help them else our enemy going to win.

This game for me is all about a flip of coin in getting good team mate (or atleast 4/5 is good) or having the worst nightmare in your life seeing your mid laner or adc giving a 10 death in around 20min of game.

And let's put some facts here, you got me(A) and my friend(B)

My friend (B) get almost a 90% of time good players who manage either to carry or atleast be decent to hold lane and win while me (A) get almost 70% of time people that like to make new meta of ashe top or skarner mid or feeder or even people first time to play ranked or ofcoruse the trolls/afkers.

And my friend is in Gold5 cause of that and i'm still struggling to climb back to s3 after getting demoted to s5 over and over due to players of that 70% i talked about, So you telling me that fair? And yes my friend is the same skill level of mine i would say, in fact most of time they either feed hard in mid lane or top lane or jg if they played it.

So is the solo/duo queue about RNG now ? Getting a good player or not ? Been judge on the performance of a whole team while in fact i find a lovely message say " You need to improve your plays else your MMR will drop more" and i'm like my plays or my RNG players i get queue with?

Like for example from 1 day i had that lovely player who was doing ranked for first time and they made a total of 8k damage in 40min while that suppose to be our ganker and objective secure person .

Thank you for reading this anyway :)