It's a logical error to look at the outcome of a process and draw conclusions about it with no other supporting data. This error would be innocuous if it wasn't the underlying cause of every inhuman prejudice we've spent the last few centuries trying to rid ourselves of.

If I were to say, "Since there are so few women contributing to open-source projects, it's obvious that women aren't capable of producing much valuable code," the hacker news server would melt from the angry response.

But apparently it's ok to say, "Since there are so few women contributing to Postgres, it's obvious that it's not a meritocracy." Logically, however, these statements are equally erroneous.

You can use this sort of pseudo-statistical handwaving to justify ANYTHING that sounds remotely plausible. That's ignorant, and that sort of ignorance should be opposed no matter the form.