Yikes! I cannot believe how much misinformation is out there about this topic. I'm writing an article about this and in my research (google) I found so many articles, blog posts, etc. about this that are completly false. Some seem to think that if you buy a premade base, ie. melt and pour or rebatch, the end product is soap made without lye. This is not true. These bases were all manufactured using lye at some point, its all there in the ingredient list. When you see words such as "saponified oils of..." or "sodium cocoate", etc. These words mean oils that have been mixed with lye (sodium hydroxide) and gone through the saponification (chemical reaction) process to create soap. Now, once this process is complete there is NO lye left in the finished product. But, that does not mean none was used, as we already discussed.
I think what needs to be clarified is if you use a premade base YOU do not need to add the lye, since it has already been done. It all goes back to not fully understanding what soap IS.
From Wikipedia: Soap consists of sodium or potassium salts of fatty acids and is obtained by reacting common oils or fats with a strong alkaline solution (the base, popularly referred to as lye) in a process known as saponification. The fats are hydrolyzed by the base, yielding alkali salts of fatty acids (crude soap) and glycerol.