This sort of thing has been discussed a fair bit before (e.g.
https://www.cubecraft.net/threads/i...nking-system-in-cubecraft.369355/post-1612879).
I agree with the majority of past comments: such a system wouldn't really suit the casual atmosphere of Cube. Also, it would probably increase the amount of toxicity present in the community, which isn't exactly desirable.
As the majority of the playerbase is rather casual, I don't believe newer players get "paired against highly skilled opponents" often enough for it to really be a worry. I think it would be even less welcoming to join and be faced with a ranking system, of sorts, of which they are at the bottom.
And, as mentioned by Luca in the post linked above, there are other ways of playing the games more competitively, such as scrims or the upcoming CubeCraft League (it is a current project listed on the public update board!).