I guess this forum made it this way to atleast, give users some time to still make some unnoticeable changes or corrections their posts incase of mistakes or prematurely/mistakenly clicking the "post" button while still typing/creating the post.
Most of the time edits within the first few minutes of the post is spelling mistakes or phrasing of the post being corrected. I know this from experience, and I expect everyone here on the forum has made mistakes. I mean sometimes it as simple as using "has" instead of "as", which I'm only remembering now I noticed I did the other day, I think I forgot to edit that one though
. Anyway, hardly any
malicious editing is done during this period, and therefore as suggested above, isn't worth keeping in the database.
However, keeping edits which have been edited after that grace period are worth keeping somewhat. For example, from a forum perspective, a user could be looking to gain popularity of a thread, get lots of replies, and therefore appear higher on the list when people sort by views/posts or simply have a thread which a lot of users refer too. Then, they could go back, and edit that and remove a malicious link or even add one. That's just one of the examples, not a particularly strong one, but there has been instances where checking a edited post has been worth the effort, and has helped with efforts of moderation. I'm just failing to come up with a really good example right now, since I'm not one of the ones which has access to that data, so I'm using educated guesses rather than speaking from experience.
Although, it also serves another purpose, on suggesting how up to date the thread is. For example, if you're following a guide on how to import a private key, you probably want to know that it's semi up to date.