The 4% rule is also important for EARLY retirees, because you have (hopefully) a long event horizon to protect against; if you retire at, say, 35, you will likely have another 40+ years you have to support yourself, and absorb market blips, etc.
Versus if you retire at a more normal 60-65, you probably have, what, 20 years to plan for? Plus your window of opportunity to do cool shit is now a lot smaller.