Remember, the difference between a tangent and a non sequitur (of which I'm also fond, though only for the sake of humor, of course) is that a tangent has at least limited relevance. Usually my "tangents" have multiple points of relevancy, which, if we're being literal, disqualifies them as tangents, since a tangent is a line (of reasoning, in this case) which touches the subject at one, and only one, point. I choose analogies and cite historical influences that affect or illustrate the topic at hand in several ways, and try to do so with enough clarity to make each way apparent with a little attention. The applicability can and often is debated, and that's fair, and it frequently extends to only a single aspect of the subject at hand, but the reference is usually relevant on multiple levels to one or more aspects of the subject.

The main things I'm guilty of are investing more time and thought into online posting than any normal person does, and often expressing myself unclearly (almost never concisely). In my limited experience, most people who read and respond to posts don't want to invest much time and thought, and most people willing to invest the time and thought don't read and respond to CMB posts.