It's not really a conspiracy. The CIA actively uses vulnerable phones, televisions, and other devices as clandestine listening devices.

99.9% of HN readers are just too boring (read: not terrorists or foreign officials) to have to worry about it.

Source?

There's a very simple reason why phones cannot be recording all the time - it would have an impact on the battery life. But an always plugged in device like the echo does not have such limitation.