Different item. While Gender benders could optionally be built with a null modem inside, as a single item their purpose was to link incompatible male and female ports.
Having both a null modem and a gender bender end-to-end was common.
Still is! I carry around gender-benders, null modem adapters and 120ohm CAN db9 resistors every day, along with usb-to-serial, peak can to usb, kvaser to usb, and ixxat to usb.
These aren’t dead technologies by any stretch, not that you were implying that.
Having both a null modem and a gender bender end-to-end was common.