The amount of background blur isnt just a function of sensor size and aperture. Relative distance between camera, subject and background all play a very important part too, so that owl shot has no relevance to the bear shots with a telephoto.Sure, if you are doing portraits, where DoF matters, you'll go with FF. The same holds with low light where you want to minimize noise. However, if I were going to visit Alaska or Yellowstone, I think I'd buy a MFT camera and the Zuiko 300/2.8 lens rather than the 600/5.6 for my Canon. The combo will be cheaper, lighter, smaller and unless I'm shooting at dusk or dawn, the grizzlies will show the same size (and probably comparable IQ) on the same size print, or my screen.
Indeed. Because we all know having deeper DoF makes for better wildlife images. For example, the first image is much better than the second, it's much better that all the distracting stuff behind the subject is decently sharp focus.
Oh c'mon neuro, DoF certainly matters, but this is a shot at 55mm with f/5.6 and a downward angle. Nobody would expect it to have a shallow DoF. If anything, this shot is an argument against the significance of sensor size, because the following shot I did with my crop sensor and it has a much nicer bokeh.
I can even get some notable separation with my iPhone if I'm shooting a subject at minimum focus distance with a background at or near infinity.