You probably have more background in data mining that the rest of us. For those of us with limited or no exposure to data mining techniques, I think the graphic gives me some background about each technique that I otherwise wouldn't have had. At a glance, I understood that there are two types of hierarchical clustering method - agglomerative and divisive. That is a small amount of new knowledge, but it's more than I could have gleaned from a glance at a block of text. I don't think the graphic is without merit.