In dia4 you get matched with people way worse than you (gold-dia4).
When you hit dia3 it instantly changes the pool of people you get matched with to people way better than you (dia-pred). Most of the players you will encounter are preds and masters.
It does not make sense. It´s not in anyway, ironically enough, skill based matchmaking. Casual games have better SBMM than this.
If your skillslevel is high diamond-low master, you will never be able to reach that goal because most players you encounter from dia3 onwards are already better than that.
It can´t be good for preds too. The only reason I see to play ranked as a predator is to practice and have a challenge (and maybe also retaining your rank). Which will both not be achieved when matching them with way lower skilled players. I think they would be fine with a little bit higher queuetimes as a payoff.
Therefore my suggestion: Put dia1-pred in a matchmaking pool and dia4-dia2 in a matchmaking pool. Everyone benefits and it still is a real challenge to climb from dia1 to masters.
Source: https://www.reddit.com/r/apexlegends/comments/ff4trl/the_ranked_system_dia_is_a_disaster/