I can't speak for anyone else, but I downvoted it because of the deadly combination of:

• A. Unfriendly snarkiness, i.e. scare-quoting "rationalists" and making very general statements about the flaws of LW without any suggestions for improvements, and without a tone of constructive criticism.

• B. Incorrect content, i.e. not referencing this article which is almost certainly the primary reason there are so many comments saying "I donated", and the misuse of probability in the first paragraph.

If it were just A, then I could appreciate the comment for making a good point and do my best to ignore the antagonism. If it were just B, then the comment is cool because it creates an opportunity to correct a mistake in a way that benefits both the original commenter and others, and adds to the friendly atmosphere of the site.

The combination, though, results in comments that don't add anything at all, which is why I downvoted srdiamond's comment.