A lot of people somehow have this notion that because Toya was initially born with a harmful quirk, he could somehow never be a great hero. This is despite there being other characters in the exact same situation(see: Deku, the main character) who overcame their weaknesses and became great heroes.
However, the past few chapters put an end to this notion, with it being more or less implied that Toya was Enji's masterpiece.
While many quirks can be dangerous to use, we have been shown through Deku and Mirio that these quirks can also be mastered via extensive training. There is zero reason to think that Toya's quirk wouldn't have worked the same way.
Even when he was young, Toya had greater firepower than Enji. While he didn't have the body to withstand these temperatures, Enji didn't even try to teach Toya to lower the temperature of his flames in order to be able to withstand them. Enji thought Toya was a failure and gave up on him. Toya subsequently never had any professional training like Deku, Bakugo, or Shoto, and instead trained himself by trying to copy Endeavor.
However Endeavor's fighting style, flashfire fist, was detrimental to Toya as it forced him to maximize his heat, even though his body couldn't handle it. This caused him to destroy his body in the process of trying to be like Endeavor.
"All he ever taught me was how to turn up the heat".
If Enji had only trained Toya how to fight in a way that was suitable with his quirk, to lower his temperatures and to focus more on physical strength/martial arts and support weapons, Toya would have easily been a great hero. Aizawa and Shinso are mostly martial arts/weapons focused and their quirks aren't even as useful as Toya's.
With Enji's guidance, Toya would have eventually made it into UA. He would have probably burned himself, much as Deku broke his arms, but it would have never been as bad as it was in the current timeline. Eventually, he would have unlocked Rei's ice quirk and through mastery of that, he would have been able to utilize his flames to its fullest extent and probably surpass All Might.
However none of this ever happened, because Enji wrote off Toya for not being a prodigy like Shoto despite the fact that Toya's potential was ultimately much higher. As a result, Toya became a villain, destroyed his body, and ultimately never lived up to his potential.
However, the past few chapters put an end to this notion, with it being more or less implied that Toya was Enji's masterpiece.
While many quirks can be dangerous to use, we have been shown through Deku and Mirio that these quirks can also be mastered via extensive training. There is zero reason to think that Toya's quirk wouldn't have worked the same way.
Even when he was young, Toya had greater firepower than Enji. While he didn't have the body to withstand these temperatures, Enji didn't even try to teach Toya to lower the temperature of his flames in order to be able to withstand them. Enji thought Toya was a failure and gave up on him. Toya subsequently never had any professional training like Deku, Bakugo, or Shoto, and instead trained himself by trying to copy Endeavor.
However Endeavor's fighting style, flashfire fist, was detrimental to Toya as it forced him to maximize his heat, even though his body couldn't handle it. This caused him to destroy his body in the process of trying to be like Endeavor.
"All he ever taught me was how to turn up the heat".
If Enji had only trained Toya how to fight in a way that was suitable with his quirk, to lower his temperatures and to focus more on physical strength/martial arts and support weapons, Toya would have easily been a great hero. Aizawa and Shinso are mostly martial arts/weapons focused and their quirks aren't even as useful as Toya's.
With Enji's guidance, Toya would have eventually made it into UA. He would have probably burned himself, much as Deku broke his arms, but it would have never been as bad as it was in the current timeline. Eventually, he would have unlocked Rei's ice quirk and through mastery of that, he would have been able to utilize his flames to its fullest extent and probably surpass All Might.
However none of this ever happened, because Enji wrote off Toya for not being a prodigy like Shoto despite the fact that Toya's potential was ultimately much higher. As a result, Toya became a villain, destroyed his body, and ultimately never lived up to his potential.
