I teach the log cabin block to beginning quilters. They've done really well with it, without muslin backing. I also found the 1/4" foot was key, also I have students measure the block when they finish each 'go round', so they make sure their blocks are all the same size.
Recently, I started a new quilt "Cabin of the Bear" and they recommend the muslin backing. My rule of thumb when starting a new quilt is always to follow the directions the first time. What a waste of time and effort. It took way too much time and I really don't feel it adds anything but bulk to the quilt. If I teach this quilt, it won't be with muslin backing.