It’s an option to do this, although I think the primary reason it’s not built in is that it’s more a workaround than anything else.
Ideally repairing the database should be manageable enough that you wouldn’t care about whether or not you have a copy of it backed up.
Some improvements are happening in this regard, but I can see how people hesitate to rely entirely on that. I spent 7-8 hours recreating my database last night on the newest canary release, which is much improved over the previous time I had to do so, but it’s still a long time.