And let's not even get started on Matt Ward (may his name be cursed for all eternity). In fact, let me just quote word for word from an interview with him from White Dwarf [footnote]It's on page 24 of edition 376, talking about the then new Grey Knights codex. I know it seems really weird that I have this to hand, but it
really stuck with me.[/footnote].
"By the same token, if slaying their Battle Sister allies provides the pure blood needed to enact a banishing ritual against Warp-spawn, then a Justicar may well order it."
Putting aside the Grey Knights' pragmatism for a moment (Mat spoke with a little too much relish when extolling that previous example), let's focus on their tabletop presence.
That's completely unedited. Games Workshop's own official magazine acknowledges that Matt Ward's a creepy little fuck. And Grey Knights killing Sisters of Battle for a banishing ritual actually got put into the codex as fluff, despite how it didn't make any sense.
EDIT: Welp, this thread has now made me find out about the Space Marine Centurions, and
OH GOD I CAN'T HANDLE THIS SHIT ANYMORE