Point of League of Legend placements for bronze?

Let me get this straight. I know I'm not amazing at league. I just want to get better, but what frustrates me is that it feels like ranked isn't worth it anymore. I ended last season as bronze 3. Yeah, I know that's pretty bad. It's just I thought if I tried super hard in my placements I could keep bronze 3 or move to bronze 2. I won 5 of the 10 placement matches, and I got placed into bronze five. I understand that everyone got knocked down the ladder, but what's the point of placement matches for bronze players if they're gonna get placed down to bronze 5. I tried super hard in all 10 of my matches, and I got A's and S's on all of them. I just want to know what other's have to think of this. I feel like I could have just fed in all 10 of my placement matches and I would have gotten the same result. I don't think riot had that in mind, but it sure feels like placement matches for bronze is pretty useless. The idea that I have to climb from the absolute bottom just feels super discouraging.