I think Japan is a 100% Photoshop country.
Reason is; their color base is CYMK. Gimp for years only support Standard RGB.
No kidding about "Standard RGB", it is really US Standard, not even close with Apple, Kodak Film & Fuji Film RGB Standard. Hence RGB in Linux Display & Print actually more darker than on Windows & Apple. It used because it is Free basically, not because quality.
Still back then, Gimp has experimental support for CYMK on Gimp 3 to deal with that issue. But Gimp 3 need more than 10 years to go production ready.
Then tablet ready. Tablet in drawing tool, not Tablet Mobile. Gimp have hard times to support them.
Imagine Japanese Mangaka usage. Both CYMK & Tablet issues really a big deal. Heck, Gimp has hard time to support mouse pointer.
Of course, while Gimp Struggle with those two subject, Krita support them more than 10 years before Gimp 3 become Stable. But I never see nor heard Japanese Mangaka or related to Publishing+Printing use Krita.