Why SBMM ''cuts out the middle man''

I'm tired.. I don't mind sbmm in ranked mode.. but every game I'm playing I'm playing against so many predators at one time.. I am not predator material.. the only reason my accuracy might seem good to apex is because I essentially sneak behind a person and empty a mag into them before they down me.. how that works I don't know but I'm tired.. I can't play this game.. I suck .. I was having alot more fun over Christmas than I am now.. I'm level 220 and everyone in my lobby is like 450+ 20kill badge 4k damage .. I've only got the 2k badge for revenant.. I've never done over 2k damage in my life and honestly think it was just a fluke.. but now I'm going against guys who can beam you with an r301 at 200m break your shields before you can even tell what's happening.. not to mention my ping sits at 180 average so now it's not just a case of be faster than the other guy.. now it's just if the first shot gets you you're dead .. because even though you got through that door way and closed the door before you were downed.. you're still technically not actually behind the door yet.. even though you are.. I'm constantly shot around corners when I shouldn't be but that .2 of a second just made the difference.. I don't have the tactics these premade predictions squads have.. I only really play randoms and ever since S4 things have just been so .. not fun.. I don't know how to get better and I'm honestly on my final tethers because it's really hit me hard just how actually ❤️❤️❤️❤️ I am at the game.. not that it's of anyone's real concern or anything I know.. but I'm done.. I'm over it.. i don't really wanna keep playing anymore..