Why so few Linux distros supported by swift.org?

Just short one question: why is a static IP necessary?

I once had one, but that got lost when the my provider (T-online or nowadays Deutsche Telekom stopped cooperating with the provider of my static IP, which later went bankrupt). It is somewhat expensive to get a static IP in Germany nowadays (the one I had was just 5 Euros a month but those times are over, today you can get this only if you are a business customer)

@mishal_shah can explain that better than I can. It is just the way that the Jenkins federation functions is my understanding.