Question: When I click on the category "Politics" to find any posts, there are none. Zero.
Are only advanced members , say level 5+ , allowed to discuss politics on this site or what is the reason ?
No I do not think that politics, is in any way restricted. Perhaps it is just a bug, there are a few on this site now and again. I would try a second time.
I found the "bug": the default position for new members seems to be "show less of politics", and you have to change that (top, on the right side) in order to see the posts in this category. Maybe they want to discourage newbies from discussing politics because that's where all the hot issues are.