That's the approximate number of rogue 'of's I have seen on Mumsnet posts today alone. 'Should of', 'would of', even an 'I of' somewhere. It is spread by repetition. Should we counter by correcting every instance we can, and enforce the correct use of 'have' by repetition?
Incidentally, my title is an old crossword clue. Do solve it if you like.
YABU: no, we should leave the 'of' people unchallenged;
YANBU: yes, let's have a campaign to correct each and every instance of the error.