Why are Pred players still to this day are able to 3 stack against diamond lobbies.]

It's been 6 years since this game has been released and I feel like one of the struggles for me in ranked especially when I get to diamond every season are the 3 stack preds in my lobby. It is so frustrating to try and climb because I feel like every lobby I can only hope that I am not queued with them. Some people might argue that it's a skill issue and yeah it is, the skill gap between a diamond and a pred is high and let alone 3 preds in 1 team. I liked the idea that HisWattson suggested where preds should only be able to solo queue or duo queue. I feel like this would make the game much less depressing for majority of the people who don't get to play 12 hours + every day. Idk I may just be ranting after losing 1000 RP going from D1 being close to D3 but what are your guys thoughts on the matter.