>I never heard a thing like Debian 12 being tied to one specific model of laptop etc
Purism does this, though not to a specific device. For the products they sell they have their own custom fork of Debian.
>if people can upgrade and install any software they want, that reduces incentive for them to buy a new phone every 3 years
You are going to be limited by the support of the BSP even if you can install any software you want. You will end up stuck on old software which may not be properly maintained especially if the OEM has moved on to supporting newer products.
>If phones were like laptops or desktops, you'd just install the Android 13 on your phone when Android 12 was outdated etc.
Google has been making efforts to make it easier to upgrades parts of Android without involving the OEM. Later versions of Android may not me compatible with older hardware as minimum specs change and architectures are dropped. For phones with unlocked bootloaders you can flash Android 13 on your phone if someone creates a compatible version of it.
>If I don't have root shell then I don't own the device. Simply. Its a useless brick and toy.
UNIX is not the only way operating systems can be designed. Considering everything that isn't UNIX as being useless is an ignorant mindset.
>As I said, its not Android the piece of software rather the manufacturers who hate users
Then what's the point of this argument if you agree AOSP is a fine way to have an OS with Linux on a phone.
>They don't provide drivers generically either as blobs or sources.
This same issue would exist if you wanted to use Linux with a different userspace.
>Why is it again, when you have two computers and you can generally install and update anything on one and can't do shit on the other?
I don't understand what you are getting at.
>is active malice where even rooting or providing you the bootloader is often cryptographically locked down.
The bootloader being locked down isn't malicious considering it lets the system prove that malware hasn't compromised the boot process. In computing if malware is running first there isn't much the system can do the detect it's existence. It will have the upper hand in the cat and mouse game. If a normal person buys a ACME brand phone, but a malicious actor unlocked the bootloader and installed malware into the OS, that user will never realize they were pwned until they encounter software that is a step ahead in the cat and mouse game and the malware isn't able to hide its existence. A user having root is also problematic because it compromises Androids security model. If a banking app saves an access taken to your phone it is relying on the security of Android that no one is able to steal this taken. If the a user is able to get root they could bypass this and steal the token and commit fraud.