Not every server owner wants to follow this license, but the point is that Reika's license often conflicts with the economic model that these servers use. Note: everything I write about next refers to public servers and modpacks. I have rethought many times how a server should look like, which submits to the conditions of Reika and I can say for sure that it is quite realizable. These requirements are perfectly acceptable.
In order to even use DragonAPI the mod dev has a very particular list of requirements/ToS/EULA/etc.