Touring - Long wheelbase for a Bob Trailer?

I would think one would want a mtb to haul a bob, but sometimes i see pics of people hauling them with true touring bikes. Why? you don't need the long chainstay because there isn't a pannier clearance issue. But perhaps i'm missing the point. Does a longer wheelbase have better handling when pulling a bob? more stable?
Or did they convert from panniers to a bob, but want to keep the option to go back?

Speaking for myself, I use my bob on my touring and mnt bikes. I also have panniers. It really depends on where Im going and if I want to ride after making camp. With the bob--just unhook and go. For touring, I use panniers, because I dont care to ride after a long day. For the weekend camping trip, the bob hauls more and is more convient to load/unload.
I dont have a problem with stability using the bob except on long downhills--over 25mph it starts to wobble if I dont keep a firm grip on the bars.

The longer chainstay provides a more stable ride which is good for both trailers and panniers. My commuter feels like a yacht and it pulls a burley nomad full of groceries(beer) like a bat outta hell.