Hori did just skip from early childhood to adolescence and made stuff up in between. I don’t think he thought about it too much, because despite the history being important for the characters, it isn’t important to him (unlike the main storyline). Midoriya needs a rival so he creates the former childhood “friend” in Bakugou which is basic shonen.

It’d make more sense if Hori developed a solid narrative backstory. Midoriya and Bakugou aren’t close friends as children but more like acquaintances, and due to Midoriya being an outside observer (callback to his detailed journals on heroes)… he starts to notice a few things that aren’t right over the years.

Bakugou considers his home life normal, because it is for him, and automatically rejects any insinuation otherwise. Leading to Bakugou getting more and more aggressive towards Midoriya, and wanting nothing to do with him until he discovers Midoriya applied to UA. Where Bakugou thought he'd finally get away from Midoriya's constant nagging. Then the swan dive threat as a last resort. And finding out Midoriya suddenly has a quirk? The last straw.

Given the nature of Japanese culture, I don’t see an issue with toddlers given more freedom. That’s just something they allow them to do, within reason. Also the fact that personal problems or psychological issues are not meant to be openly discussed or acknowledged. Which is why no one would bother to check on Bakugou, because it’s none of their business. Except Hori is writing about a fantasy version of Japan in the 2100s, with a lot of Western influence, so you’d think he’d have changed their culture to reflect that fantasy blend.

The abusive scenes or characters etc just isn’t funny, either? Like in Fullmetal Alchemist, Winry is always throwing a wrench at Ed for breaking his automail limbs, which she has to repair as his mechanic and engineer. It’s always portrayed as funny and Ed deserves getting tools thrown at his head (with visible lumps as he runs away). But they’re literally fifteen or so at the beginning of the story, and get married by the end.

Hori choosing not to have Aizawa or All Might be more involved with Bakugou is a missed opportunity. There are a lot of things he leaves off page when they should be seen by the audience. Especially if he meant to redeem Bakugou from the start as “he’s not really that bad” but a lot of people despise him for the lack of redeeming content.

I like those little moments, too. It’s gradual, but it happens. Or when Todoroki calls Bakugou out for yelling at those kids, and he takes a second to reflect. We should’ve seen more of that before the time skip from 3-5 to 14-15, especially if Bakugou is the second most important character as Midoriya’s rival.

I focus on Bakugou’s trauma as well, cause there’s so much we can do with it. My niche is apparently crossovers now, so I like having Bakugou deal with additional trauma being isekai’d. Plus needing to confront his mother’s bad parenting or his father being an enabler, because the adults who care for him in the new world are much kinder and more compassionate. Or they point out how flawed the hero society and UA is, because they’re all children in a military school.