Because the scale of these companies gives them immense power and control over people's devices and (digital) lives. The size of the corporation leads to a geometric increase of power through network effects.
Now that you have an answer, what are you actually trying to ask? Do you have an issue with megacorps providing more control to users?
Now that you have an answer, what are you actually trying to ask? Do you have an issue with megacorps providing more control to users?