My uncle is a certified Stihl Dealer and service technician and I asked him about that one day. He thinks it is because other countires that are logging rain forest trees like to use the 090/070. He said the like them because they are simple to work on and because they have used them so long it is what they know and what they have acquired parts for so they won't change and go with the newer saws. he said that down in south America their go to saws are the Stihl 090/070 and the Echo CS2100/1201. I have watched some Youtube vids on a channel called the "Mansur forest". it looks to be a Aisin country. They are cutting giant Rian Forest trees and all they use is a stihl 090 or it might be a 070. It's kind of crazy how they log them there. The guys doing the falling are wearing wife beaters, shorts, and wear flip flops or rubber boots. They don't really make face cuts but instead cut the root swells all around the tree and just let it go where it's going to go. They do it 3rd world style for sure.