A computer (or a smartphone, basically whichever type of Turing complete Von Neumann machine you use) is your interface to the modern world, from interacting with your government to the stores you frequent and talking to the people you love to the media you consume.

So in that sense I think it does matter who is the ultimate arbiter of what it will and won't do, not only in an individual sense but a societal one. The more people switch to something they themselves control, the less power third parties have over their behavior.