Why does apple not allow to install previos versions

I'd like to know why this is too, I sold my old iPhone 3G after upgrading to iOS 4, it was shocking! And I kept calling up seeing if I could downgrade, and no luck, I don't really understand why they do so.

 

Minimizes fragmentation in the installed IOS base. If everyone upgrades and no one downgrades it insures sunset of the older IOS's

Just look at Android as an example of how bad it can be.

 

They want to stop jailbreaking. It's literally that simple. Fragmentation has nothing to do with giving users the choice to use an older version so long as they always allow you to upgrade if need be. Up until the iPhone 4 (or shortly before it, I don't quite remember), Apple allowed us to install older firmware versions. There wasn't a complaint to be heard, as far as I am aware.

The issue with Android is that certain handsets are not seeing updates even become an option. This is not the same as giving users the option of using a different build of the OS. Also, fragmentation on Android is as much (of not more) influenced by hardware as it is with software. This is not the case with iOS devices.

 

Are you sure? I swear I'd been hearing about backing up SHSH Blobs long before iOS 4 came out.

Am I wrong?

 

I had no problem going back on my old 3G. You can Google the previous iOS and save it to your desktop then restore in iTunes. It will ask you what software you want to install and simply single click and then hit OK.

 

Like I said, it may have been shortly before. I'd say it was just before iOS 4 came out. My point is that it wasn't always like this and there were no issues as far as I am aware. At least not "fragmentation" issues. If you feel like you have fragmentation issues with iOS you could always just update to the latest version. Problem solved. No more fragmentation.

They want to limit jailbreak and their "reason" for wanting to limit jailbreak is to thwart piracy.

 

It has nothing to do with piracy.
Proper app authorization to prevent piracy on a mobile device is not hard to implement.

It's all about $$$$
Apple wants to limit jailbreaking to make sure all your apps come through the App store and not a competing app store like Cydia.

It ensures revenue stream.

 

Personally, I don't think it has anything to do with jailbreaking or piracy.
The number of users that jailbreak their phone is extremely small compared to the total user population.

This is about support and app requirement consistency IMO.
The fewer the number of official releases, the easier it is to support.

 

Hence "reason" in quotes!

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Except that Apple has gone out of their way to bash the previous jailbreak into the ground every iOS update, be it big or small, not to mention they publicly fought to make jailbreaking illegal.

 

Bingo.

Ensuring that users can only install the latest iOS release means that it's harder for people to jailbreak or perform an unauthorized unlock on their device.

This helps enforce both Apple's walled garden approach and the carrier's locking policies.

Restricting old updates really doesn't help with fragmentation. I doubt that people accidentally download an old .ipsw file and try to install it on their device. If you're doing that, you're doing it on purpose.

There's nothing that forces people to upgrade. I know people with iOS 5 compatible devices that haven't upgraded.