What I've heard from people installing solar at home is that even though you install solar and a battery, you are not allowed to disconnect from the network unless you are a rural property.
I don't know about this one, but I'm not sure why you would. A lot of that investment gets paid back by feeding energy back into the grid - you would be throwing money away.
Net metering is under heavy pressure from utilities because it costs them a lot. They'd also like connection fees to pay for the infrastructure they have to maintain, even if you aren't using (much of) their electricity.
I don't think that is the case at all. From a practical perspective many people probably choose to stay connected (particularly in the southern states) to ensure they have a reliable energy supply over winter.
Sure you could guarantee your energy and completely disconnect from the network with enough power walls and solar panels, but the capital investment would be relatively huge - so it will be a principle based decision and not based on pure economics.