Ah yes, I see now. Pardon my brain fog. It had not occurred to me that anyone would run without these on. I thought you were alluding to some sort of mod.
The dust shields commonly crack between the bolts mainly on the LH side for some reason.
Many people just take them off rather than repair or replace.
My 77RRC didn't have them when I bought it.
But as it turns out they do have a function other than snagging the wheel when you are trying to fit it on the hub.
Regards PhilipA