Two possibilities:

• P6 doesn't support RSS yet, because the RSS specification is far too new. (RSS 1.0 came out in December 2000, well after P6 was underway.) Thus it behooves Raiph to report every little piece of gossip, no matter how small, because otherwise how would the interested hordes find out that not much is happening?
• There's a friendly competition with Diaspora to see which project can get the highest ratio of press releases to actual users.