I think all of these are true:

1. Apple is big enough that it needs to take care of edge cases like offline & limited cell reception, which affect millions in any given moment.

2. Launching a major UI feature (Siri) that people will come to rely on requires offline operation for common operations like basic device operations and dictation. Major UI features shouldn't cease to function when they enter bad reception zones.

3. Apple builds devices with great CPUs, which allows them to pursue a strategy of using edge compute to reduce spend.

4. A consequence of building products with good offline support is they are more private.

5. Apple didn't even build a full set of intents for most of their apps, hence 'remind me at this location' doesn't even work. App developers haven't either, because ...

6. Siri (both the local version and remote service) isn't very good, and regularly misunderstands or fails at basic comprehension tasks that do not even require user data to be understood or relayed back to devices to execute.

I don't buy that privacy is somehow an impediment to #5 or #6. It's only an issue when user data is involved, and Apple has been investing in techs like differential privacy to get around these limitations to some extent. But that is further downstream from #5 and #6 though.

Dragon Naturally Speaking was way more accurate than Siri is now, and it was on-device on ancient computers.

I don't care if I have to carefully say "bibbidy bobbity boo, set an alarm for two" - I just need it to be reliable.