For Gandalf specifically, it helps that he was a powerful wizard, which opens up itself to lots of fun card designs, and that his character evolves significantly throughout The Lord of the Rings, Turian explains
While those extra copies further help increase cube consistency and raise the floor they don't help Sphere get high ratings
If another creature you control dies at the same time as Pitiless Plunderer does, you'll get a Treasure
Since you will be sacrificing artifacts to Flamewars ability (ideally treasure tokens), you might as well get some value out of it
Its a flex, sure, but its also a way to preserve a card thats central to your deck and your playstyle
Jeskai Control may run it, but I feel Ionize is probably closer to what theyre after than Absorb