Thank you for proving my point. Lineage is not a factory supported OS, and having to manually upgrade to an alternative OS qualifies as a hack in my book.
You may consider it a hack but to me, the ability to install the OS of my choice on MY device is a necessary feature we should never let the manufacturers of our mobile computing devices (yes, that's IS what a smart phone is) take away from us. That's why I'll never buy an iPhone or any other iOS device, or even any Android device with a boot loader that can't be unlocked.
An OS shouldn't have to be "factory supported" to considered a valid choice. Tying the software and hardware into a single inseparable package is a step backwards for flexibility and user choice.
Even if you don't have the technical ability to install an alternative OS yourself, you should have the right and ability to have someone else do it for you. Only unlockable hardware gives you that option.