Most of what makes NTFS different than FAT probably doesn't need to be backed up. Complex ACLs, alternative data streams, shadow copies, etc, are largely irrelevant when it comes to making a backup. Just a simple warning "The data being backed up includes alternative data streams. These aren't supported and won't be included in the backup" would suffice.

All of that stuff matters when you're using the backup for its intended purpose: to restore a system after hardware failure.

Unix tar is obviously not the right solution, but a Windows tar seems like it shouldn't be that hard to do and yet we are in the situation we are today. I've been using dump/restore for decades now on Unix, including to actually recover from loss, but I admit that it's not that pleasant to use. I like that it is very simple and reliable however, unlike the mess that is Time Machine (recovering from a hardware loss on a Mac is a roll of the dice, and I've gotten snakes) or worse Deja Dup. I'm not sure I've ever successfully recovered a system from a Deja Dup backup.

I think the use case for disaster recovery is a bit different than long-term archival.

Does anyone buying tape storage actually use it for archival rather than disaster recovery?

We do. We have vast amounts of data that we merely have to keep around for a decade or so for compliance purposes that would rarely be accessed, so it goes on tape and off to Iron Mountain. Then we have backups where we need to be able to recover a running system from some 'known good' state, which is somewhat complicated. The former is conceptually tape drive+tar/cpio/etc.; the latter is an expensive setup that includes some proprietary solutions.

> using the backup for its intended purpose: to restore a system after hardware failure.

No. The intended purpose of a backup is to restore the data (such as the Frogger 2 source code) after a hardware failure. If it has the side effect of also producing a working system, that's good, but it's not the point. After all, the hardware necessary to build a working system may not exist any more; one (only-probably not the last) instance of said hardware just broke, after all.

The metadata matters.

Your one trivial use case isn't all use cases, and it sure isn't my important one. If you're doing more than backing up your personal workstation, metadata is extremely important. If I ever have to restore something, even just data, out of the multi-petabytes we have on tape, I better not have to manually go through it to figure out who should actually have access to it before I make it available to the people who need it.

If you’re backing up a db or something sure, but for a file server this can be just as important as the data itself (ex: now everyone can read HR’s personnel files which had strict permissions before)

The format is extensible enough that it could be added

That’s fair; I wasn’t really considering windows. It seems like there ought to be some equivalent by now though.