I don't know. To me, "would of" is not a typo such as "mroe" instead of "more" caused by a slip of the fingers, or skipping over a word because you are hurrying, and it's not a minor mental slip such as continuing a short-term pattern of apostrophe use, e.g. "the cat's over here, the cat's over there, the cat's everywhere and the pigeon's are in a state", and it is not in the same category as the mixup between "your" and "you're", because both are in very common use - "would've" is in very common use but "would of" is not (500M Google results for would've plus would have, only 5M for would of).
"Would of" gives me the impression of someone who either doesn't read much (where do you ever see 'would of' in a formal published paper or book outside quotations/dialogue?), or doesn't pronounce what they say clearly (because if they did it would reinforce that 've and of are different), or doesn't pay enough attention to what they are writing to think 'oh that's not right'.
It was also because it was in the midst of a post about how the author was great at a foreign language and should have been allowed to finish schooling sooner, even though this is the sort of mistake that seems to be made more by uneducated people which would counter the idea that leaving school sooner would have been a good plan.
I was trying to draw attention to it by butchering a famous speech to make it stand out, and because I don't just want to say "dumbass ha ha", but wonder whether it is in a different class of mistake to the usual mistakes seen on the internet (possibly along with "if I would have known" - how can people say that instead of "if I had known" without realising that it means something completely different?).
Also, interesting how as soon as I posted it it was voted down, then over a day or two it climbed back to +4 or so, and now has been knocked down again. What kinds of people are doing which kind of voting?