Yes Comatose, the mentioning of "endowed fabrications" and that the Inquisitor's endowed powers are a result of Hemalurgy means someone would have to
use Hemalurgy to create the Inquisitors. And who is above the Inquisitors? The Lord Ruler. It follows, then, that the Lord Ruler would create such endowed fabrications through the use of Hemalurgy, which means the Lord Ruler uses Hemalurgy.
It's important to remember--at least, this is my understanding of it--that Inquisitors probably don't actually use Hemalurgy on a regular basis. The Inquisitor's powers are actually a
result of Hemalurgy on them--that the Lord Ruler used to create them. So, whatever our knowledge of Hemalurgy is, it is all second-hand. It is involved in the "process" of creating the Inquisitors.
Whatever we see of the results of said process (like, knowing the Inquisitors push away the mists) does not really help us determine what the "process" is.
Of course, on the flip-side, it is possible Inquisitors can create more Inquisitors with more Hemalurgy. From a pure narrative standpoint, Brandon has to explain how Hemalurgy works. The Lord Ruler isn't alive to tell it, so therefore, someone else must have knowledge of its workings. In order for Brandon to be able to tell us, a non-Lord Ruler character knows what this Hemalurgy business is all about!
(And also, a non-Lord Ruler would have to explain that the thing Vin released is named "Ruin", since Ookla confirmed that the name Ruin is referenced a lot in the book. Needless to say, this is a very important person
)