I’d be curious to know how many widefield DSLR astrophotographers do or don’t callibrate their frames. I think a lot comes down to what camera you’re using.
About 10 years ago, I started out (I would imagine like many beginners) doing astrophotography with a very low-end camera. I found a compact Canon Powershot can get you nice pictures of M31, M42, etc, but I absolutely had to callibrate those frames because the sensor was rubbish. The same seems to be true of low-end DSLRs, e.g. a Canon EOS 1000D produces rather scratty frames at ISO 800 or 1600, yet I’ve seen many astrophotos in online forums taken with it. Yes, you can get impressive images without callibration, but you can do a lot better with.
I don’t doubt that if you use a Canon EOS 5D (I think the camera Graham uses?), you can push it to a very high ISO setting and still get nice clean images. But I wonder how many beginners are willing to splash out on such an expensive camera?