Sorry but stopping thieves/malware is not worth the economic damage that manufacturer repair monopoly brings to the consumer.

You can make your phone 100% safe by turning it off and encasing it in concrete but having to pull out the pneumatic hammer to make a call is prohibitively expensive and very much not useful.

Moreover security is a poor excuse anyways as many measures taken by manufacturers do not improve security in any way. And for those that do, there are ways to achieve that security without harming the consumer.

Manufacturers are tilting the scale in their favor to such a degree that I'd argue should be made illegal because it damages society as a whole. There is a reason antitrust laws used to be enforced way back in Microsoft's days.