Do you know that
Signature Campaign is an invention of bitcointalk.org?
I didn't know before now. I had thought that signature campaign is something that has been in practice even before creating the bitcointalk forum. But I was surprised to discover otherwise. I searched the internet for ways to earn bitcoin. Many blogs including binance news acknowledged that signature campaign is a means to earn bitcoin and it was started or it is exclusive for bitcointalk forum. Even
99bitcoins said a similar thing.
In my opinion, the concept of signatures is not only available on the bitcointalk site. I once joined a local community site that probably used the same CMS as bitcointalk and had a signature feature under posts. However, in my local forum there is no signature campaign so the signature space is usually filled with words of wisdom or promos about products/services
I assume the emergence of this signature campaign is because the bitcointalk site is a large forum so many companies want to advertise their products here, but because the bitcointalk forum does not provide advertising space, the trick to being able to continue advertising on this forum is to rent signature space from forum members.