It's not really a politeness thing, although some people may just not want to mention it because they like their own privacy. Also, keep in mind that most of the time, people who go to forums are wanting tips on how to do better. Folks with the masters may be a group that tends to do just fine, which would mean many are not here at all. And mtnsurf, good work!
Now 20795 masters overall. 2522 Categorization Masters as well. I think one can expect more masters in the coming days. More selection from India will enhance the party mood among turkers.