Hello back Russ, Thanks for the welcome.
When I was first introduced to the bow bar was in the early 70's in the Black Hills of South Dakota where I grew up. Right around Mt. Rushmore, and if you have ever saw the Mountain, you will get an idea of the terrain there. From Custer State Park to the foothills around Huillett Wyoming there is lots of Ponderosa pine, and spruce ( some Canadian Blue ). There are lots of areas where skidders and crawlers can't get to. Some that are either to steep or to rocky.Back then ( I don't know about today ) they still pulled logs out with the help of mule teams in some of these loggable areas.
The bow bar was handy for large areas ( some several thousand acres ) of new growth, such as after forest fires and such where equipment was impossible to get to.
Bows are also used on some of the larger tree's when thinning and spacing also but I personnally have never used one on timber over about 9 or 10 inches. Anything over that would go back to the straight bar.