The PC software ecosystem has been open historically, even with Windows and OS X, and now there's talk of it being replaced by a completely closed alternative
If Mozilla and Google both do X, but Mozilla's actions are judged as "open" while Google's are judged as "completely closed," then the words open and closed are losing their meaning.
How does Google's other business activities affect whether, in principle, an HTML/JavaScript-based OS is "open" or "closed"?
Yes, it's true that OS platforms are moving towards sandboxing their apps more and more. This is mainly being driven by market forces, because more sandboxed platforms offer important features:
- more resistant to malware
- more secure (one stupid little app can't steal/delete all your data)
And while mainstream consumer devices are moving towards being more sandboxed, the ability to tinker is being addressed in other ways, like Raspberry Pi, which are very cool in their own way.
iDevices are locked down for the purposes of Apple maintaining iron-fisted control over the platform at the expense of both developers and end-users. Chromebooks are locked down for end-user security and ease-of-administration.
Chromebooks allow the end-user to unlock the bootloader and/or run them in developer mode if they really want to do that (and this is all well documented by Google, not akin to jailbreaking), and pretty much the only reason a lot of developers even consider Chromebooks as full laptop replacements is for this reason.
Want to run Firefox on a Chromebook? Install crouton (a project developed by a Google employee) and just go ahead and run Firefox, works fine, just like any other Linux app. Google does nothing to stop this (in fact, they go out of their way to make tools to enable it), they just put enough friction into it to let you know that when you do this all bets are off as to the security of the chroot you are running native Linux apps in.
There are legitimate benefits to having a locked down platform which Apple (and developers/consumers) have decided is worth the negatives. There are zero viruses or malware on iOS compared to quite a few on Android. The quality of applications is significantly higher on iOS because (a) developers have a consistent platform to optimize for and (b) majority of iOS users are more than likely on the latest release.
This approach is working so well for Apple that Google, Samsung and Microsoft are all trying to emulate it.
I don't disagree that there are benefits to the consistency of the Apple ecosystem versus that of Android, but all of those benefits are rooted in Google's lack of control of what phone vendors do with the OS (though they have been working to change that), not lack of control of users or app developers.. the entire jailbreaking ecosystem proves that such freedom doesn't harm the people who want the safe thing, it is just a shame they are forced to constantly fight against the phone vendor (on the Apple side) to keep things open whereas Google (usually -- they've been uncharacteristically dickish with Chromecast hardware) usually goes out of their way to allow the user to run free if they want to.
Of course, for some 15-year-old girl in Jakarta, "learn more about their world" may in fact mean rooting their machine so they can deal with grotty Unix details and 8 years down the road build on that to for an MEng thesis and then startup.
What does that have to do with how open the devices are?