Nether in the Skyblock server

On this server, you can enter the Nether world like in any Single Player world by building a portal from obsidian.

However, in this case, you will appear not in the usual Nether world, but on a new personal island, where biome is set to Nether Wastes.

What is the purpose of having a personal Nether world?

The only purpose of it is to build platforms and wait for the usual Nether mobs to spawn.