Free, Casual, Advanced is at least in my view similar to difficulty settings (ie: Easy-Medium-Hard) and one's ability to enter into said difficulty. This isn't a way to demoralise people and say, "you're not skilled enough for Advanced", no, this is more to guide people on the expectations and ease of entering to their chosen roleplay.

I just think you're getting mixed up on what level you would like to enter and you're not seeing what it is that you're looking for when you're checking out the threads. A casual Roleplay is generally a minimum of two paragraphs and some people will want to post more. I know that I personally like to add in several paragraphs in my posts so I will only ever look in the Casual and Advanced sections for Roleplays. :)