Not everyone has the perfect past where they can excitedly and positively speak about it without a healthily amount of censorship or just sugarcoating it. With any kind of skeletons from the past that people wish to step over, there isn't going to be many willing to face the problem head on and tend to either outright ignore them or forget about them. Things like this are normal psychological responses to a significant amount of stress coming at one time. So when these response pop up in anime, there is usually some interesting foreshadowing for where a character is most likely going to grow.
When it comes to the current season, and a couple that are has extended from the previous season, there a quite a few. The first one being Golden Time where Banri is trying to figure out what past he forgot; of course, as he starts to remember his past, thing get significantly more messy and less of a clear path of where he will end up. There are far more anime around different subjects regarding the past, but the other anime that I want to point to is Silver Spoon and Hachiken's not-so-wonderful parents.
Forgetting
When it comes to amnesia, there initially was out of Banri's hand as to whether he actively trying to forget his past or not. The thing that is being emphasised now is that Banri has been having these panic attacks, when he remembers everything, and as a result he is trying to prevent himself from changing. Ever since he started college, Banri made friend and even snagged himself a girlfriend with his lack of memory from the past, so it's clear why he doesn't want to remember his past. When it comes to "new" memories, it is difficult to not change and the uncomfortable nature of change makes it difficult for a person suffering from amnesia to fully cope an issue like this alone.
At the end of the day, it is quite clear that Banri is actively trying to forget what he has forgotten in order to keep his current personality. The reason as to why Banri want to stay ignorant it clear, however, the way he continues to run from his problems dug his own grave and it feels more like he is slowly turning into his old self despite the struggle. Plus, with the cliffhanger of Kouko breaking things off -- at least as of writing this -- is the consequence of him running away from his past after they both had such a discussion previously only it was more focused on Kouko and the car accident.
Pushing Aside
Turning to Silver Spoon, we have more of a issue with other people rather than an internal conflict. This fact makes it that much easier to run away from, and unfortunately, that is exactly what Hachiken does when it comes to his parents.
I had a post that covered the importance of parent development as a character, but some could argue that I've been far more lenient on the assumptions I've made about the Hachiken family. It is legitimate, but I want to focus more on Yuugo this time around considering he is the one trying to avoid more bad blood with his parents -- mostly his dad. And disliking, or even hating, your own parents is a bit difficult to trying and avoid them considering they are the ones who raised you, but it is an order of magnitude easier to if we are comparing to the situation that Banri is in.
So like the first season of Silver Spoon, there is an inherent notion of needing to face difficult situations in order to grow. It is up to Yuugo to actually stand up to his dad and be able to express something he hasn't been able to do for most of his life of studying and trying to impress his father.
Finding Traces
It is almost like clockwork, mainly because it is a tool for foreshadowing the thing that was trying to be covered up tends to resurface. It shows that you can't always completely get rid of some haunted past that you wish to either forget or ignore. If a character can't face something that is at least moderately difficult, there isn't any room for them to grow; and that is what makes things like a hidden past that a character tries to leave behind, something that both make them more interesting it also serves as a good device for character growth -- stacked in with story progression.