They have the function so they can ransomware televisions. Want to use the TV? Just send them a Satoshi or two every year and they won't shut down your TV remotely. The fact they can use it in case of theft is a side-benefit.

And rooting is pointless on its own. They're going after it as if it were a personal attack. So you need to full-on pirate instead. Phone bricks itself if rooted? Run a pirate OS that emulates the checks and "phones home" to your laptop instead of its central processor in order to bypass the ROM-built-in checks. We have a right to root our phones, won in court, but that won't stop companies from treating it as worse than murder, it's an ever-escalating battle.

'Samsung seems to be trying to discourage users from modifying the software on their new Galaxy Z Fold 3s, giving them a message that unlocking the phone’s bootloader will render the phone’s cameras unusable (via Android Police). This isn’t the first time we’ve seen phone manufacturers pull this sort of trick, but it seems to represent an escalation in Samsung’s fight against its users who want to gain complete control over their phones.

An XDA Forums user confirms that after unlocking the bootloader, the Z Fold 3’s cameras were completely non-functional: facial recognition, loading the camera app, and trying third-party camera apps all failed for them. The user reports that re-locking the bootloader made the cameras work again. ' Aug 24, 2021

Rooting won't even help against malware built directly in to ROMs.

Yes, until you won’t be able to anymore.