@aldebaran I can answer this question!
The altnet was an experiment I did in November. I fired up an alternate sbot network using a unique shs cap. It totally works! But I ended up turning it off, because the population was very low and I felt as if I was splitting people's attention between the two networks. It makes more sense to encourage people to join the main network, as you mentioned.
Why one would want [an altnet]
The use-case is sbot for organizations. If you have a group of 150 or 3,000 people who are working on a project and would benefit from being connected on a social network, then you might want an sbot altnet.