It doesn’t charge to 4.2V per cell but instead to 4V or 4.05V.
Using the same charging chips as lithium that terminate so high would damage the cell.
Also the voltage drop is a lot more (4V->1.5V vs 4.2V–>3V), so lithium charging chips would detect it as a deeply discharged lithium cell and only charge at 40mA or so instead of fast charging or even a damaged, shorted out battery (so not charging at all and giving an error). So a problem on both ends.
It doesn’t charge to 4.2V per cell but instead to 4V or 4.05V.
Using the same charging chips as lithium that terminate so high would damage the cell.
Also the voltage drop is a lot more (4V->1.5V vs 4.2V–>3V), so lithium charging chips would detect it as a deeply discharged lithium cell and only charge at 40mA or so instead of fast charging or even a damaged, shorted out battery (so not charging at all and giving an error). So a problem on both ends.