@Axs5626Sxa5001 I feel that sbmm doesn't need to be in BR pubs. But in Arena where you go against the same team multiple times, it's necessary for good matchmaking experience. At least a loose SBMM, certainly not as strict as what you face.
But if you Solo-queue, the matchmaking is weird. I certainly get easier lobbies, but my teammates are lvl 10-100 so I have to sweat it out. I have a 52% win rate iirc, but I am as frustrated as you are. I certainly don't agree with '50% win rate' solution, because it isn't making me any happier. That's exactly what I am frustrated with actually, because the game is trying too hard.
I have quit total of 5 games after round 2 in total 90 games, because it's frustrating to babysit a Lvl 10. I am by no means a serial leaver, but sometimes I can't take it.