I figured you’d say that, but I don’t get the argument; you could say that about anything. Any faceless Toa could have worn the Golden Armor to defeat the Rahkshi on Bara Magna; any faceless Order member could have fallen into the Antidermis and gained the knowledge of the Makuta; any faceless Toa could have been sent to free Tren Krom.
And, even after that, I would argue that there would have been difference had it been anyone but Vezon doing that stuff. A faceless Matoran sent on a suicide mission to Destral wouldn’t have followed a Makuta deeper into the fortress after completing his mission just to see what’s up; a faceless Matoran wouldn’t have looted that fortress as it was being attacked; a faceless Matoran probably wouldn’t have proposed a bargain with the Cursed Great Being; heck, a faceless Matoran couldn’t even have activated the Olmak in the first place for it to be fused to him, though I’ll admit that that’s a particularly weak argument.
I don’t think the suicide mission would even have worked without Vezon; I’ll admit that I’m not 100% sure about this, but my understanding of the mission is that Vezon was instructed to only tell the Makuta about the attack, but then the Order also told Vezon about the “sabotage”, knowing that he’d try to betray them for real and give the Makuta the story that the Order really wanted them to hear.
This plan would only work with someone ambitious enough to try to actually betray them, yet stupid enough not to realize he was being manipulated and weak enough to not actually be a threat.