The new mail-Art Projects

A lot of new mail-art projects I see lately are simple of construction. The mail-artists thinks of a theme. Want the network to send him/her mailing (postal system only). What is the reward for the senders? Their artwork will be documented on a blog, and that is all the documentation that will ever be made.
For me it seems like a trade that isn't in balance. The artwork and sending costs a lot of money. The digitizing and making of a blog entry only takes a few minutes. I can understand that a lot of old-time mail-artists don't send in things to projects like these. Are these the modern times where the digital information is all we can afford for documentation?