I don't believe they will retire and stop working entirely. They can start a business
I believe flexibility is the main achievement they are hoping for. So yes quit and 'retire' for 3 years, maybe to have children or travel the world or both. The main objective seems to be to work hard save harder then actually live a proper life outside of the big city smoke and be a normal family of some kind not caught in the rat trap that is often modern working for many.
Its one of the most sensible ideas modern generations have come up with. The rejection of conspicuous consumption is something to be lauded as we waste so much and value little in modern economies. Its great to see people finding ways to learn skills to avoid waste and paying others for this saving drive etc.
Commuting in both time and money to me is such a waste of humanity, every step away from that traffic jam pollution failure of a business model is an advance for all of humanity imo. It is questionable if people of plain working class skill set can thrive as easily as the more elevated professions both in money and demand they can command but imo if people can learn trades like carpentry its possible (there is always demand for honest work and so leverage to achieve this fire concept).
So, in your opinion, skills are better than having a business for retirement plan or 'FIRE' plans, well that could be true cause if you have an on demand skill and it's something you love doing, that certainly could be the best retirement plant ever, but what about investing in your talent too, like let's say football or music, are painting, e.t.c, or maybe you have a talent in business too who knows, IMO, I think FIRE plan should be something you love doing and that brings income so as to compliment your retirement