I think the issue some people have is with the word “understand”. Understanding is tied to mental capacity. Saying someone can’t understand something is saying they aren’t smart enough to grasp a concept. In other words, it can come across as saying someone is too stupid to get it. A better way of phrasing it would be, you weren’t here to experience what we did, so our outlooks are going to be different, but this is why the past was so bad..

I am in no way saying that anyone is calling anyone stupid. I am just saying the phrase “too junior to understand”- while not intended to be degrading/derogatory- can be perceived that way. Kind of like saying, “no disrespect, but…” then saying something disrespectful.