When ogs used the Elo calculation formula identical to EGF’s except in its handling of 13x13 and 9x9 data, ogs put a lot of effort into aligning its strength scale with the rest of the world, particularly EGF and KGS. Player polls and surveys were conducted, and when misalignment appeared to have gotten too large, there were site-wide ranking adjustments.
By the time we switched to Glicko2, ogs had become one of the largest Go servers in the Western world, and the priority had naturally and gradually shifted, in my opinion, so that the ogs scale making mathematical sense within ogs in terms of “1 rank = 1 stone handicap” on the ogs data became more important.
Aside from this handicap issue, the strength to rank assignment is not science, and there’s no right or wrong about it. Unless you are talking about the inclusion of 13x13 and 9x9 performance into the rating calculation, please read Go server rank survey
(S_Alexander is not kidding in saying “dan certificates are sold”) which was a part of the reasons why the priority shifted.
If you are saying the inclusion of 13x13 and 9x9 data is “quite apparent mismatch”, we know about it as discussed between me and anoek in this discussion above.