Hard to believe some of the drama here about post counts. In the spirit of transparency, I'll disclose my reasoning for going along with the suggestion to exclude OT and Lobby posts from post counts:
Post counts have no real function other than to show how active a member is. They don't tell you anything about how reliable a member's information is, how good a player they are, what their teaching/building/luthier credentials are, etc. Some vbulletin sites have activated a feature called "Rep Points", which was designed to allow members to give feedback on the information given by other members; the idea was that if somebody made a useful or helpful post, they could get positive feedback on that post, and over time, this would be reflected in their "Rep Points". In actual use, features like this usually become a popularity contest dominated by those who spend the most time hanging out and shooting the breeze online and have nothing to do with the content/value of posts whatsoever (to see how the concept of "Rep Points" can turn into a total wankfest parody of itself, visit a certain forum dedicated to home recording that shall remain technically nameless here).
So what is a newbie to do if they want to check into who is giving them advice? Looking at the post count of any member can at least tell them who has been active in the topical music forums, and to what degree they've been active. This isn't much, but it's at least something. If someone with 10,000 posts on a music forum gives you what seems to be good advice, you might be inclined to take their steady activity on the forum to possibly be a sign that they're at least well-read on the subject. Would you think any differently if you discovered that 9,900 of those posts weren't about music related issues at all, but were instead about things ranging from "Asian chicks rule" to "The return of the son of man laws, part 17", to "who thinks farting on an elevator is funny?"? I know that I'd rather, if i were going to be looking at post counts at all, be looking at a count of music related posts.
I honestly can't think of another reason why a post count should matter at all. If a poster is posting for the fun of it or the community - both perfectly valid reasons - why should it matter what the counter reads? If the poster is posting for the counter, IMO the poster might want to take a look at their motivations. YMMV, as always.