Every mobile device sold in North America is unlocked for carriers. That wasn’t the case back in the day. Also locking down macOS has been for security. It’s way ahead of other operating systems for sound and app security.

Carrier locks have nothing to do with security or walled gardens. Two things using the word 'lock' is mostly coincidence.

And getting rid of carrier apps was a positive but it was moving from one walled garden to another.

And that happened a very long time ago. It provides zero defense against accusations of apple changing for the worse.