Try that while raising a couple of children.
It's great in theory when you're healthy, in your early 20's to early 30's, when you are independent and have no dependents, when you are living in a climate that is favorable, and when you're living in a city.
If any of those circumstances are not met you'll be either in a lot of trouble or you're most likely going to change.
Those that don't have the option to change we call street people.
And living off other people's couches and/or fridges and such does not make you an independent.
I can see a good reason for doing with 'less stuff', but this extreme is simply not realistic on anything but the smallest of scales.
It'd be tough if all your friends decided to do it tomorrow and you'd all want to sleep on each others' no longer existent couches...
In the future when nobody has enough money to buy a house or a bunch of stuff in the first place we'll probably be seeing more nomadic seniors.
Those couples that I've met that did the 'RV thing' after their pension typically saw it as a way to do all the traveling that they had missed out on while in their working years, a way to reward a lifetime of hard work.
I used to read Steve Roberts digital nomad site for some time and I found links to familes living on sailboats and travelling but it seems those links are gone. The above was the first one I found on google.