Are you seriously acting like every application having full access over other applications is not an actual security issue?

It is for netflix, or the cloud image storage provider that wants to secure against the consumer easily extracting data and going to someone else. The user being able to easily take a program made by a third party and have it completely rearrange the guts of any other program is the basis of consumer security in a world without a unified government keeping commercial interests at bay.

It is, but nothing can be done about it. That's how Linux permissions work. Any app running as me can execute any other app I have permissions to run. It can pipe stdin/out/err, trace it, etc. Why should the desktop apps be different?

See my other comment too.