They were an interesting idea that - like most things Pokemon - were underutilized and underrealized - but I have to appreciate the novelty. I was hoping they would play a part in Swish, given their supposedly world-ending or at least world-changing significance in SM/USUM, but I suppose I hope too much with regards to continuity and lore out of this franchise. Still, considering James Turner conceived them, it's especially surprising they didn't play a part in the story - especially even moreso considering Eternatus' general aesthetic.