I think it's actually a pretty big deal than you're saying.
Firstly, Yoshio was one of the strongest player in the 1970s. Nowadays, despite not being as strong as he was, I wouldn't say he's equivalent to 2100Elo master. If you assume that the top player is 2800, a +700 difference mean something like .9999 probability for the top player to win against Yoshio (which practically means always). I doubt that would be the case. It's more likely that a winrate from .66 to ~.85 to be more appropriate. In other word, Yoshio would be ~2600ish ELO. That would still be an underestimate of Yoshio's strength imo.
Professional dan denotes past achievements, not playing strength. Young 1p is actually more likely to be about half a stone to a stone stronger than some older pros.
It's fairly hard to quantify how strong 9d KGS or AGA are, since there are too fews of them. But if 9d KGS is ~1 stones weaker than the pro, add on 3 more stones and Crazy Stone would be ~ 5d-6d KGS, which would be 95-98% percentile or more! That would make the computer about ~2100-2300 Elo for chess. Correct me if I'm wrong, but 10 years ago, no go program would have even come close to a mid rank kyu players.
Sorry, I know that the ranges given in the post are quite broad and might look silly, it's just hard to make any direct comparison between the system
I think .66 is substantially too low. Iyama Yuta is well over 50% against any professional in Japan, and while Ishida is still competitive in Japan, he's not a title contender anymore. So I'd wager that Iyama is at least a 66% favorite against Ishida, and Iyama is himself not 50-50 against the absolute top players (40-60 perhaps, maybe worse).
Professional dan denotes past achievements, not playing strength. Young 1p is actually more likely to be about half a stone to a stone stronger than some older pros.
It's fairly hard to quantify how strong 9d KGS or AGA are, since there are too fews of them. But if 9d KGS is ~1 stones weaker than the pro, add on 3 more stones and Crazy Stone would be ~ 5d-6d KGS, which would be 95-98% percentile or more! That would make the computer about ~2100-2300 Elo for chess. Correct me if I'm wrong, but 10 years ago, no go program would have even come close to a mid rank kyu players.
Sorry, I know that the ranges given in the post are quite broad and might look silly, it's just hard to make any direct comparison between the system