While I agree with your point Open-source is not a silver bullet. I don't see anything other than Open-source as a good enabler.

Yes, pushing back is possible with closed source as well.

The real question becomes, which is harder? and for who? To push back at closed source, you'd have to be a big consumer of them or atleast big enough to be able to sue the vendor. If you're an individual, you're in real trouble. Of course, there are people who play both roles.

And I see Open-source as the best enabler for technical individuals. As far as i can see, of course.