Yup... It's true. Now let's talk about it. Briefly.
What is soap?
Soap is made through an exothermic (releases heat) reaction called saponification. During this reaction, fats and oils are "saponified" or quite literally "turned into soap". Typically you don't want to use the word in it's definition but that's exactly what it means. Saponification means "to saponify", or, turn into soap. As the fats and oils saponify they get harder, creating the magnificent block of goodness we use to cleanse our skin of the nasty stuff it collects from everyday life and the environment around us.
In short... bar soap is a hard block of fats and oils.
What is lye?
Lye is an alkaline (very high pH) metal hydroxide originally derived from wood ashes. The process has become more refined and now is done by breaking down a salt water solution into different compounds. This "new" process is called the "chloralkali process". Lye most commonly refers to sodium hydroxide or potassium hydroxide. Sodium hydroxide makes bar soap, while potassium hydroxide makes liquid soap. Both are dangerous.
In short... sodium hydroxide lye is a caustic substance that makes a hard block of fats and oils. You cannot harden the fats and oils into soap without lye to cause the reaction.
When someone says you can make soap without lye by doing "melt and pour".... that's not lye free soap. Melt and pour soap is regular soap where the lye process has already been done for you. Let's say that again! It's not "lye free soap". It's soap that's been pre-made for you by professionals so you can color it, shape it and fragrance it without the fear of dealing with the lye.
So when some people say "lye free", what they really mean is "pre-made". This is not a discredit to melt and pour soapers! There's some very talented melt and pour artists. I love melt and pour as well! It just doesn't change the fact that sodium hydroxide is still on the ingredient list.
If someone is claiming that their soap is "lye free!" they are flat out LYing to you (Ha! That wasn't intentional, it just worked out that way).