It just hit me!! To further add onto the 'Machia wasn't originally supposed to be AFO's confidant/just a Vanguard member/The Muscular Before Muscular', if that's the case, it does explain a certain design detail for both Muscular and Machia.
Both Machia and Muscular wear cloaks as essentially their means of disguise when not in combat and trying to blend in. It could be possible that the decision to take Machia's story in another direction could have been during mid-Training Arc, with the cloak design being essentially an 'out' if Hori wanted to go or stick with the current direction. If this is true, as we know, Horikoshi took the new direction and gave us Muscular instead, though did go ahead and give Machia a new cloak design as likely a call back.
Of course, I could just be overthinking things!! I just like thinking about the 'what if's of My Hero Academia's story, and the idea of someone like Machia having a different role than intended. Thinking about Machia as another Stain follower is just so interesting to me, that it's a shame the story, again, just doesn't do anything with his debut.
Also, would this mean that Machia would have originally been the one to kill Water Hose? Eh, not too, sure on that, esp since he did seem slated to stick around, but I can't say its impossible. I will say, if Machia was supposed to fight Deku early as the brute of the group, given his importance in hcapter 57 as apart of the 'Stain 3', I doubt he'd be shelved by Horikoshi? He might lose, but night still be strong enough to recover and escape. Of course, I say that and we know what the fuck happened to Mustard so who knows XD