In fairness, in the linked post, only the x-height of each character is 3 pixels. The task the designer of 3x3 set for himself was to create a typeface where each character could only be 3 pixels high and wide at most. That said, the work in the linked post is a very clever and precise exercise in optical illusion. It works wonderfully and is ideal for cases where a design calls for legibility at such a tiny size.