I would like to preface this theory with the fact I have read neither Dragonsteel Prime nor Isles of the Emberdark, so this may end up being very wrong.
In Wind and Truth, we learn that there was a fourth moon of Roshar that crashed, bringing the total number of celestial bodies in the system down from 17 to 16. There are 16 Shards. There were 17 people who killed Adonalsium.
In The Way of Kings, Hoid says, "I began life as a thought, a concept, words on a page. That was another thing I stole. Myself." My personal take on this is that it related to a prophecy of sorts (I may be completely wrong) - if Preservation had good enough future sight to see several millenia ahead, I suspect Adonalsium would have, too.
My theory is that perhaps Hoid was referring to a prophecy about himself, involving him becoming a Shard, which he chose not to fulfill (thereby "stealing" himself from fate?). Potentially, Adonalsium intended for him to be a Shard, thinking there would be 17 Shards - and so 17 would become a significant number instead. Then, they crashed the fourth moon when they realised they were wrong so the Rosharan system retained its significance.
Why the system had to be notable, I'm not sure, but perhaps it has something to do with Braize's strange metals?
Obvious flaws in the argument:
If Adonalsium had such good future sight, how did they not see this coming? Perhaps it was only a slim possibility, like how Hoid thought Retribution's Ascension was unlikely?
If the fourth moon crashed into Roshar, it would have been catastrophic. But the listeners were there when Honor and Cultivation arrived, which was, presumably, just after the Shattering. My only theory against this is that perhaps Adonalsium (or their remnants) preserved them, but that is a weak argument at best.
Any thoughts?