Well, first is the terrible matchmaking... but besides that, most people play sheep meta champs and right now meta champs have almost everything in one kit. New champs also... mobility cc dmg tankiness, etc.. and + runes, even if they didnt' have something, they do now.
So even if you win your lane against someone like irelia/riven/vayne etc... they're gonna come back in the game if your team isn't doing well like you.
If you're not playing like 2-3 divisions above your lvl, you have to win your lane AND get a good team if you're going against meta sheeps, which in solo q, most of the time you are. Because those champs are just too overloaded and too hard to stop with this insane dmg in the game on your own.
There's no room to think, there's no room to wait and just cs and get stronger in the game anymore. Everyone is just qwer - boom, you're dead.
That feeling like you don't have any impact on the game whatsoever, just who coin flipped a better team, IMO is worse than losing. Feels like you're just going through the motion and waste your time to see what kind of a team system offered you today. Lame.