So that, if the opponent went for Dark elixir first then they cannot lure CC troops, And if the opponent went for luring CC troops first they wont have enough troops to reach dark elixir storage later in the battle.
Also dark elixir and clan castle is placed just opposite from each other. So it leaves no vulnerability on any sides of the base.
And since it is a symmetrical in the form, so we placed all the defending buildings evenly on this base. And we placed all the important buildings in the core compartment of the base. it will slow down every ground troops, because they need to break through every single compartment in other to get the 3 stars from this base. Also this base will defend well against ground attack strategies too, because of the too many closed compartments. Because we build this base prioritizing on air defense. If you are looking for the new town hall 9 base that can stand stand really good against every town hall 9 attack strategies specially from air attack strategies, then you can use this base design.