I presume that everyone knows that if you join a Collections Project, all your observations that qualify will display that project in the Projects panel on the right hand side.
So for keen users who are contributing significantly to one's project, one could ask them to join the project, not only to see the journal updates, but to have the projects as a "badge" on their observations.
The issue is thus which unknown and unjoined projects an observation might contribute to. There might be many dozens of these ( there are over 7000 projects), so merely displaying them all would be a huge clutter. Perhaps an option would be a button to "show all projects that this observation is a member of" - which would open a panel with a list of the projects?
I am sure many people are unaware of project that they are contributing to, that they would love to join!