Why no dust cover?

Lots of "reasons". You nip a curb, damage it, it rubs the flywheel, damaged, won't stay on, lazy mechanic. Of course in this day, we are all finding parts that have been junked, often/ most of the time missing hardware and "accessories." Easy to see, after 40-50 years, "they are missing." Some of US are missing a few things along the way................