I Think the Ranking System Good
The whole system of having guardrails up in Poke and Great ball tiers and then giving you a final test in Ultra against only real players is good for people new to the game. If you put enough time in and are trying to improve; anyone can make it to Master.
It's also calculating your elo and acting as your "placement matches" for Master. When you break into Master Tier you are on the real ladder and rising through the Master ranks really means something.
If you're more casual at Pokemon there is no shame in stopping your ranked climb in Master and collecting your rewards, and if you're an intermediate player who climbed out of Master Rank 4 you should feel proud.
I also really appreciate that the top rank of Champion is a real accomplishment to strive for, and I hope that one day I'll be good enough to reach it.