So, last post I talked about how criticism of certain drawing styles stems from the fact that critics might speak a different dialect of visual language. The Art Perspective would have trouble recognizing the idea of graphic dialects because it sees drawing as a siphon for drawing "real life," which leads to the second reason why people might deride certain styles:
Reason 2: They see an issue of skill, not fluency
Rather than seeing graphic ability as a proficiency in a set of communal standards (fluency), people regard drawing as a "skill" that people are "better" or "worse" at. In the Art view, this skill is often determined by how accurate real proportions are held up. Judging representations based on iconicity gives an "objective" basis for claims of value.
Granted, the communal signs of the visual language community may not be prevalent as standardized signs like in spoken language (largely due to the forces brought this Art Perspective). However, within an individual author's style, they have consistencies and patterns. But, you really can just tell when someone is or isn't fluent, based on your own fluency.
I should also note "fluency" makes no judgment about the nature of the content. It purely has to do with reaching a certain degree of proficiency with drawing. Indeed, there are several very popular comics both on the web and not that are very well written and have great content, yet I'd say that their authors are less than wholly graphically fluent.
The fact of the matter is that Liefeld is undeniably graphically fluent: he has internally consistent and patterned ways of drawing and does so to a high degree of proficiency within that style. Sure, his proportions and anatomy may not be accurate to "real life," but this is only an issue if you believe that drawings should match real life, as opposed to patterned mental structures.
Aside from the issue of fluency levels, it is these same issues that lead people to think that certain drawings might be more "primitive" than others, like Egyptian drawings or cave paintings. Appealing to iconicity lets there be a scale of "progress" relating different styles to each other (like the notion "we've progressed so much in drawing since those old days"). Systems using point perspective and shading are believed to be "superior" to those that are flat or fixed to a certain angle-of-viewpoint, because the former is more iconic. A Language view doesn't allow this: all systems are equal, only they do things in different ways.
And finally, a thought to sum up the way that Art can (and does) fit with a Language view: Language (including visual language) is what a structure is, Art is what you can do with it.