> It is your assumption that the perceived threat is a 'nation-state'...

... That was the opening sentence of my paragraph that demonstrated that there is no such thing as "guaranteed security". If you think that there is such a thing, then you're going to be confused about many things when you think about security matters.

To the rest of your comment:

You need to keep things in perspective. [0]

* On Windows, Mac, and Linux malware can read and write to anything that the user who installed it has access to. It can read what other programs have stuffed in to RAM... including your password manager's temporarily decrypted passwords. It can often record and exfiltrate the contents of one's screen and the output of one's microphone. It can often install keyloggers that capture banking, email, and other credentials. It can often encrypt personal data, lock the computer, send the computer user a friendly ransom note, and then decrypt that data once payment is received. Unless the malware is ransomware, it can do all this without ever notifying the computer user.

* On Android and iOS, malware can do exactly what the pre-installation permissions list says it can. Malware cannot read or write to data for which it does not have permission to read or modify. For instance, malware cannot be a keylogger unless it requests the replace system keyboard equivalent permission. For Android malware to read what other programs have stuffed into RAM, it -effectively- has to be authored and signed by Google and baked into the system image.

* Are you old enough to remember popup web advertising? Because (other than the platform) that's exactly what the section you quoted from that article is talking about. In the PC world, popups are called "annoying" rather than "malware".

Is the permissions system good? No. However, it's dramatically better than what you get in the PC world.

Remember that Signal is software that is intended for rather secure communications. Signal's threat model [1] requires that other programs running on the system be unable to tamper with the data that Signal puts into RAM and on to disk. You can get those properties with a PC, but so many non-technical users' PCs have been hit with real malware ages ago that that's kind of a lost cause. Actual "take over your computer" malware doesn't exist in either the Play Store or the App Store. This is really good for the average computer [2] user.

> Maybe this is because I am also taking into account Android's severe updates problem...

Wot? Other than the ~3 year update window problem, this hasn't been a wide-spread problem [3] since Google put critical system stuff in the Google Play Services package (rather than baked into the system image) ages ago.

> I've read and understood the same things you have...

Read? Maybe. Understood? Clearly not. I hope that you'll take the presence of strong differing opinions backed up by sound reasoning and hard facts as a signal that some of your fundamental assumptions about the topic are incorrect.

[0] Indeed, maintaining perspective is a significant part of talking about security issues.

[1] Learn what that means if you don't already know.

[2] Mobile or otherwise.

[3] Yes, you can point to abandoned phones. I can point to people with missing limbs, but that neither means that the majority of people are missing limbs nor does it mean that there's a severe missing limb problem in the human population. :)