Why projects don't allow newbies to participate? We still ask a lot of questions and we're also noticeable
Because it would lead to big spam on this forum. Another reason because newbie's signature is very limited only text, which isn't attracted to other reader.
Seconded on this answer. Thinking off that anyone could simply register on the site and if a certain bounty campaign would allow newbies then for sure spamming would really be there and lots of participants because its really as easy as 1,2,3. This is why most of them do require atleast JR. or some of them do require Member and up in able for you to join.