Meanwhile locking down those apps so the only apps with a certain signature can read from your WhatsApp means that if you want to back up your messages or read them for any legitimate purpose you're now SOL, or reliant on a usually slow, non-automatable UI-only flow.

...and this gives them more control, so they can profit from it. Corporate greed knows no bounds.

I'm glad that modern computers are more secure than they have been

I'm not. Back when malware was more prevalent among the lower class, there was also far more freedom and interoperability.