I feel the same way. The way people talk about how ZFS is incompatible with Linux feels like debates over religious doctrine.

Licensing concerns that prevent distros from using ZFS will sooner or later also have adverse effects on end users. Actually those effects are already there: The constant need to adapt a large patchset to the current kernel, meaning updates are a hassle. The lack of packaging in distributions, meaning updates are a hassle. And the lack of integration and related tooling, meaning many features can not be used (like a/b boots from snapshots after updates) easily, and installers won't know about ZFS so you have to install manually.

None of this is a worry about being sued as an end user. But all of those are worries that you life will be harder with ZFS, and a lot harder as soon as the first lawsuits hit anyone, because all the current (small) efforts to keep it working will cease immediately.

Hard links[0].

[0] https://en.wikipedia.org/wiki/Time_Machine_(macOS)#Operation

Shadow Protect by StorageCraft was brilliant. Pretty sure MS actually licensed Shadow Copy from them, but I could be mistaken. It's been a while since I played in that space.

Ah but this is really not true. Volume shadow copy makes snapshots of files and through that it can make a backup of an entire NTFS including files with a lock on them and fully quiesced. It was invented for that exact purpose. Backup software on windows leverages this functionality well. It took much longer for Linux to have something similar.

I have many criticisms of NTFS like it being really bad at handling large volumes of small files. But this is something it can do well.

The lock prevents other people from copying the file or opening it even in read only, yes. But backup software can back it up just fine.

I never claimed absolute correctness, just stating what I see with the other BSD users I know.

I have to strongly disagree with you that GPL is a religion. While there Are certainly people who sound religious in nature when they talk about the GPL, The real reason it is important is because of what it forces developers to do on behalf of the users. It balances somewhat the power between the developer and the user.

Under other licensing, developers wield an extraordinary amount of power over the users. Yes, The user could opt not to run that code, but realistically that isn't an option in the modern day. Developers can and will abuse their access to your machine to serve their ends regardless of whether it adds value to you or not. For example, how much data collection is in nearly all modern software?

Perhaps you would argue that what I've said above only applies to a very tiny minority of users who have the technical skills to actually utilize the code, and everyone else It's just a religious argument. I don't fully disagree with that. There is another clear benefit That even those untechnical users received from the GPL, and that is the essentially forced contribution back from companies who want to build on top of it. I don't think there's any better example than the Linux kernel, which has gotten lots of contributions from companies that are otherwise very proprietary in nature and would never have open sourced things. This has benefited everyone and has acted as a rising tide lifting All boats. Without the requirements in the GPL, this most certainly would not happen.

My response to it however, is that those users still get a good amount of protection because The code is out there

I get what you mean and probably there are people like that, but I consider it mostly an exaggeration.

Simply - the GPL has some clauses enforcing some obligations (to prevent some rights from being taken away from you, the end user - according to their wording, and I agree), these and other clauses make it legally incompatible with the inclusion of ZFS (CDDL license) in the Linux kernel (GPL). You can build it yourself (so indeed as a user you get to not care or obey) but not distribute it (this is the problem of your distribution's maintainer).

Canonical's lawyers think this is not a problem if the ZFS code is distributed as a module, instead of compiled into the kernel itself, and since 2016 Ubuntu shipped with ZFS support.

The BSD license is considered perfectly compatible with the inclusion of CDDL licensed code and therefore many BSD distros ship with ZFS (and Dtrace) out of the box without legal worries. Indeed Oracle hasn't come knocking.

TL;DR: it's not a vibe. Some licenses are compatible with each other, some aren't. It also depends on how different licenses come into play into a "finished product" (e.g. kernel module vs monolithic build)