That's exactly why it's recommended Mitzy, because it doesn't have any "special" ingredients. As Jimmy said, it isn't good because it will miraculously sort out your skin, it's good because it won't make it any worse, which a lot of other cleansers can.
OP I use the cleanser and moisturiser (yes, as recommended by my dermatologist!) However this is really only because I'm a tight arse. She also recommended a LRP face wash that I liked (physiological gel, possibly now discontinued?) but Cetaphil is just so cheap, especially if you buy it at Costco. Again, I was using LRP moisturisers at the start too (Effaclar H and Toleriane Riche) but they come in a teeny 50ml tube and Cetaphil is 5 times the size. I do have to order it into my Boots though.
I find the Cetaphil moisturising lotion quite sticky BUT it has never irritated my face, which the LRP used to do when I was first on my acne treatments. So this, combined with the cost, is why I keep using it.
Good luck with it all BeaBoo, I first saw my derm in Feb this year and haven't looked back, I am so happy with my skin now.