Well people doing that are certainly off-grid as well. You likely heard it in reference to that and assumed it only referred to their specific situation. Like when someone says "my off grid homestead" They are saying "My homestead that is not reliant on the grid (public utility services for power/water/etc)."

The homestead is the part that means they live out in some rural area and grow all their own food.

Even for them I dont think it would be right to say they have no ability to change things though. In a revolution places like that become safehouses or food suppliers. They are also actively choosing not to participate in consumerism which is a great way to go against the capitalist class. It is true though that many of these people are the right leaning libertarian types. Yet the infrastructure they build can be seized and utilized by the revolution in a time of need, and the skills they are developing for self sufficient living, should they ever become adequately agitated, would be quite useful to a revolutionary movement.

But regardless the off grid part is just an adjective that means not reliant on public utilities. It can apply to all sorts of things. For example a solar powered Ham Radio setup could be described as "off-grid radio communications"