i love him that’s why i need to see him tortured to within an inch of his life covered in his own blood and tears
dunno if I should call this a headcanon or a theory and I know Horikoshi just went with what looked cool but the more I think about Dabi's initial design when he came to the League in the context of what we learned about him and what we saw happen to him during the second war, the less sense it makes that his body was already in that state.
according to the anime, he was learning by watching Endeavor's videos online. before Sekoto, he wasn't learning from any source at all and went about his training intuitively, but after Sekoto I strongly doubt he would be actively practicing his quirk, for a multitude of reasons. his body was still healing from the skin transplantation, the trauma associated with accidentally burning himself to death, plainly not having a place to train a fire quirk, which tend to be flashy and to use your quirk in public, having a provisional license is required, otherwise he risks getting arrested. he did a very good job staying out of the public's eye for the 7 years since he escaped AFO, who was also implied to be unaware of Touya surviving for so long.
so as far as we know, all he did for those 7 years is lay low and be very online. which makes his remark to Spinner hilarious ngl, at least Spinner sprung up to action as soon as he saw something that had inspired him, while Dabi had spent 7 whole years sitting on his very personal trauma and not going to therapy.
when Giran brings him to Shigaraki, he doesn't share any information about Dabi save for him being very invested in Stain's ideology. no criminal records, maybe, but not even a word of his absurdly strong quirk? no mentions of arson at all? they did discuss Toga making it to the news, so Dabi being left out like that was a bit weird in the context of the conversation, like him seeking out Stain's contacts was enough reason to let him join the League. he won't be useful to you, Shigaraki, but he's got the spirit. please take him in, he has nowhere else to go?
if you really look at the way Dabi uses his quirk until MVA, it's noticeable how he seems to have no idea what he is doing. there's no technique, no finesse to his moves, just throwing out huge blasts of fire with his hands and hoping for the threat to leave him alone.
when Shigaraki attacked him (fully provoked) his reaction was too slow to summon any flames at all, and if it weren't for Kurogiri, that would have been it for Dabi.
When he is fighting Geten and starts going beyond his limit, he scares himself with the increased fire output. because, yup, overusing his quirk by accident was the source of his trauma.
the databook puts his technique as the weakest of his stats. his power is huge and eventually allowed him to become the strongest fire quirk user in the BNHA universe, but his technique was extremely lacking.
all of the above just doesn't paint the picture of someone who has been consistently mastering his quirk for 7 years. rather, it gives the picture of someone who had just started using his quirk for the first time in years, having background training from his childhood.
it's not even that Dabi isn't hardworking as hell or doesn't have the potential to be trained, because he's a complete opposite. continuously going beyond his limit, despite his own body getting in his way, mastering Enji and Shouto's complicated techniques they have worked for weeks/months/years on in a matter of minutes after just observing it. surely, he has been watching Enji and learning the way his father uses his quirk for years, but putting theory to practice? i doubt he even had the chance, before joining LOV.
he had to wait, because starting to actively use his quirk sets the clock into motion, counting down the time he has left. he is like a candle, destroying himself with his fire, until nothing is left at all. he had to make sure his plan of revenge will have a chance to succeed before fully committing to the 'Dabi' route, a slow and agonizing process of cremating himself by continuously using his quirk. because when he really starts using his quirk for long stretches of time? this is what happens to him.
to conclude this post, I know why the final design was chosen (because it's cool as fuck) but after analyzing the crucial points of Touya's story and his relationship with his quirk, I really think him joining the League with post-coma design would have made more sense. once he had started really using his quirk, his body would slowly degrade to the state Dabi's was in, because his fire literally melts his skin. but his body already having 40% surface third degree burns, when he didn't even use his quirk the entire time, perfectly holding up up until the first war arc and then quickly starting to burn down? idk, seems a bit inconsistent?..
anyway, i love the concept of Dabi's skin slowly and inevitably burning down after he had joined the League. him losing more and more skin until there's barely anything left, when he reveals himself to his father and is bitter at the lack of recognition, because burning himself to the point of being unrecognizable was one of the many sacrifices he had made to be finally seen by Endeavor.
also, more of this. because this was bittersweet as hell