Demon God Pillars are too convenient

I ended up fighting to get Ozymandias on my side. Ozymandias used the Holy Grail to transform into the sun god Ra... or rather, a Demon God Pillar! Though it's apparently a genuine one, just looking like a Demon God Pillar. I've been thinking since the last chapter, but aren't Demon God Pillars too versatile when used as a framework? You can incorporate them into Noble Phantasms, they can serve as vessels for other beings. What even are they? But, I won... They're gentle compared to the Knights of the Round Table, though. I don't want to fight them again. Ah, Lancelot and Agravain weren't dealt with yet. Nooooo!