Ditto what Dorymae said. Experience has taught me that there is a world of difference between 'safe to use' and 'cured'. A soap is safe to use when saponification is complete and there is no longer any un-reacted lye present, but it's still 'half-baked', so to speak. It still needs to cure.
Curing does several things:
1) Hardens the soap as water evaporates.
2) The pH of the soap lowers as it reacts with the CO2 in the air.
3) The microscopic chemical reactions still going on inside the soap help to make the soap to be as mild as the recipe will allow.
4) Those same micro-reactions also help to bring the soap's lathering abilities to full maturity.
There may be more things, but those are the main ones that I can think of off the top of my head at the moment.
In short, curing helps one's soap mature to the best that it can be, according to its particular formula.
Selling anything before that point of maturity is reached is much akin to selling a half-baked cookie, if you ask me.
IrishLass