It was one of the options in ~2016 and it was inexpensive. As of late last year anyway, it was still the FET being used. It is still less expensive than better options, we’re talking $0.25 vs ~$1.00 at 1k qty, but it has significant impedance at all voltages. Also worth mentioning: Mtn fet drivers do not feature transient suppression, which matters for high amp builds if MCU’s other than T13A are to be used. Also the OTC cap used is likely not thermally stable enough to support firmware’s which feature timing based mode switching, so when the light gets hot, the mode switching behavior will change or otherwise malfunction.
If you build your own driver you will achieve a superior result. Use a TA driver board or one of Del’s driver boards, they are shared on OSH park. You could order the boards with 2oz copper from OSH PARK if you are building a high amp driver. The 2oz boards are only .8mm thick though, so you may need a GND ring spacer, or solder a solid core wire around the GND rim, etc.
I have a superior design to any other Fet+1, but I have yet to build and test it.