Having experienced instability I’d say that is a pretty good reason. It’s one of those things that don’t matter until it happens to you, and I think everyone assumes won’t happen to them.

Having said that it can be managed. It’s infuriating when your OS just stops working, but if you have good backups and can roll back the system quickly it’s fine.

Rolling releases are great for having the latest versions of software, but it’s also like constantly being a beta tester. And the distros approach to rolling release makes a big difference.

Manjaro does have a small development team compared to other big name rolling releases, so it just isn’t able to do the same level of testing and prep as a better resourced distro like Fedora for example. It does a reasonably good job with a small team but it inevitably makes things more difficult.

Manjaro is also Arch based but it’s not Arch, and one source of breakages can be using AUR. I think people think of Manjaro as just a more convenient version of Arch but Manjaro is it’s own distro, and using the packages in the AUR can break things. People seem to forget that Arch is bleeding edge while Manjaro does hold packages back for testing, so the two distros are not in sync.

If Manjaro is used as Manjaro and not treated as arch-light then it’s a fine distro. But it’s somewhat pushed as an easier to use version of Arch, so then inexperienced users in particular can get into trouble trying to use things like the AUR. But Manjaro itself is generally fine.

I personally don’t recommend Manjaro to people. That’s because for me there are better rolling release distros which are better resourced (such as OpenSuSE or Fedora), better options for systems stable systems, or if users want Arch then Arch itself is the way to go. Manjaro is absolutely fine but I wouldn’t say it’s the best option in any category, including Arch based distros.