Why is glicko->dan/kyu non-linear?

[gamesorry]

Specifically, it seems the conversion formula is an exponential function:

OGS has a new Glicko-2 based rating system! [2017]

10k is 9.0k to 10.0k . The ratings to ranking math is not as pretty as it is under the EGF model, it’s 850*exp(rank*0.032) where 30k is rank 0. For instance, 9k is 1664.4 and 10k is 1612.0.