A very long time ago motherboards were like that. You couldn't flash the firmware without first physically moving a jumper on the motherboard (btw what you're asking for typically would be done with a jumper, not a switch, AFAIK).
I remember a very heated argument with a friend of mine when I got my first mobo that didn't require a jumper to be physically modified to be able to flash the firmware. I told him it was heresy and that, invariably, exploits would come.
Note that these first mobo that could see their firmware flashed without requiring changing the position of a jumper had literally not confirmation asked of anything. You'd just flash the firmware by running an exe.
[1] https://wiki.mrchromebox.tech/Firmware_Write_Protect
[2] https://chromium.googlesource.com/chromiumos/third_party/hdc...
It’s amusing, because back in the 80’s we used to have a saying: “Beware of programmers who carry screwdrivers.”