I am guessing ...

... that the point of the comparison in Fog Everywhere - which Dave Lull sends along - is that there are perfectly good sentences, communicating much, that are lacking verbs. I use sentence fragments myself from time to time. Neverthless, in expository prose, and especially when advancing an argument, I think a subject-verb combination is likely to prove essential. In other words, if one want to predicate something about fog, rather than simply describe fog, a verb will almost certianly prove useful - especially if your auditor or reader wants to know what you're trying to get at.