Absent underlying qualitative differences, there is rarely a good reason to break a continuous distribution into discrete groups for modeling purposes or for model performance evaluation[1].

But for human consumption (and I believe this article is an example of that), it can help. It's basically an ocular Hosmer-Lemeshow; not a rigorous or even consistent approach to model performance evaluation, but often interesting to those consuming the model's output. For example, we do it here to give students a sense of what their chances have meant historically: https://www.parchment.com/c/college/college-1404-University-...

[1] See the Hosmer-Lemeshow test, now uncommonly used.