I'm going to be the voice of dissent and say I find the post count to be very useful at times.
Not at the high side. I could care less. Some people post a lot. Some people have been posting for a long time. Others have been doing both. Awesome. Let's give them ding dongs (or in Manny's case, ho-hos).
Where I find it useful is when someone has a post count in the single digits. Just one small factor, but I'm a lot more hesitant to put a ton of time into a response to someone asking "tell me how to do weathering?" with a total of two posts to their name, because who knows if they'll even be back to read it? Doesn't mean I won't respond, but I won't go "all-in", and will usually try a qualifying question to 1) see if there's a response and 2) narrow down the topic.
So from that standpoint, yes, I find post counts very handy. Though I could care less if they just stopped at 1000+.
Your comments have much validity and I agree with your viewpoint. The fact is post counts are relatively benign and as such are just another source of info about the commenter that can be taken into account; or not. No harm, no foul.