Compare with programming, where overt effect and actual competence are not always related. Criticizing programming and programmers is nontrivial, and hence people have to do it all the time to build up a shared understanding of good and bad practices.
Looking at visual arts, you'll probably find a similar asymmetry between drawing (where it's difficult to get to even a barely mediocre level) and layout/typography (where it's easy to do something that looks "good" to the layman yet is totally horrible). Needless to say, there are more pages bashing bad layout and bad typography than there are sites dedicated to bashing bad drawings.