Why would you never sew over pins with a serger?

First of all, you never sew over pins on any sewing machine because the needle might hit the pin and bend or break. Secondly, you never sew over pins on a serger because the pins might get caught on the trim blade and cause a malfunction or damage to your machine. In both cases, before a pin gets to the needle, either slow down or stop for a second to remove each pin.