Keep in mind that the problem with contemporary academic philosophy is not that it is insufficiently tolerant of dissent. The field practically self-defines as an unresolvable argument and the archetypal intro to philosophy curriculum involves learning and analyzing the debates between philosophers who disagree with each other about the most fundamental issues one can disagree about. Students are usually graded on 1) how well they learned the philosophies they studies and 2) their ability to put forward interesting thoughts of their own on the subjects discussed. The grading spectrum for a paper looks something like: Incoherent (F) -> Failed to understand source material (D) -> Repeated Source Material without saying anything interesting about it (C) -> Makes an interesting, but derivative or tangential point (B) -> Makes a central or extremely insightful point (A). Whether or not the student flatters the professor's own views is at worst good for half a letter grade in my experience.

Now the situation may be worse in other subjects and that may well affect the strategies the students are using-- but this says more about the situation in high school (where these students learned to write like this) than it does about college. Indeed, in my experience students often do poorly on their first philosophy paper precisely because they've failed to recognize the need to change strategies.

Also, the grading for blog comments is very likely to be only a participation grade and the students are likely to know this.