Though they're easily removed without a reinstall, it'll clear out things like startup apps and background daemons. Kernel extensions (which should be rare already, but still exist) will also get wiped.

The OS files itself may be immutable, but you’re still wiping your user data, all installed software, and other clutter stored in writeable locations.

I consider volumes local to the device as something that gets wiped on OS reset, although I definitely understand the confusion.

I'm not just wiping root and leaving home/mail/etc alone. I'm wiping and re-partitioning the local drive.

The partition layout on macOs is fairly complex - on those machines it would be comparable to "Erase all contents and settings" option, but also with a refresh of the immutable OS to the latest released revision (Not always the case on macOS, depending on your recovery drive configuration).

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That said, I don't buy Apple products for personal use - they're far too hostile to their users for me to give them money, and I was always a "function over form" kinda guy in the first place, which is not Apple's market. Apple is the chauffeured car of the computer world... Smooth, Expensive, Hands-Off. I don't always want to drive manual, but I'm not willing to give up the steering wheel... so windows, linux, and bsd for me. Although lately, less and less Windows.