Ok, why?

I'm not arguing. I don't see the difference, however I'd like to know. And what's the difference between charging a Pb, NiCd or NiMh pack like this? I can't speculate on LiPo/Li-ion because I don't know that much about them.

The cells are never perfectly balanced and depending on the quality of the pack may not be balanced at all. They pick each cell out of a bin and solder em' on! I'm sure each cell is tested before assembly, the good in one bin, the bad in another.