So at least some MSI laptops with a MUX switch are bugged.

Tested: GT73VR:
Nvidia GPU: will not output to HDMI or Displayport in the Bios when selected:
The option does absolutely nothing, as if MSI forgot to hook up the inputs.

HDMI=DFP1 (what? no HDMI1?)
Displayport=DP2 (what happened to DP1?).
Laptop panel=DP0.

In "AMI Graphics Output Policy" selecting DFP1 or DP2 does absolutely nothing.
External monitors work fine in windows. Which is useless if you need to do something urgent in the Bios and your panel is broken!

Intel iGPU: EDP1
works perfectly fine:
HDMI=HDMI2
Displayport=DP3
No problems outputting to external monitors in the Bios but it won't do it automatically.
Untested: GT75VR, GT75 Titan, GT83VR, GT63 Titan, GT72VR, GT62VR.

Laptops hardwired through the iGPU are obviously not affected. E.g. GS65 and similar should not be affected.

If you want to test to see if your laptop is bugged:
1) unlock your Bios with Paloesco's instructions in his thread.
2) plug in an external monitor then reset the laptop and enjoy the black screen.
3) see if the output ports work in AMI Graphics Output Policy so you can stop enjoying the black screen.

(Blind method to switch to external monitors in case your monitor is dead IF YOU ARE ON THE iGPU already:

GT73VR Kaby lake only (skylake has an extra menu somewhere, I think AMT configuration?):
4 finger salute combo or manually unlocked menus with FPTW64+AMIBCP 5.02 (# of arrows may change if you forcibly set a menu to Supervisor to forcibly unlock something that does NOT appear with the 4 key combination)

(unlocked bios only):
Right arrow, Up arrow x8, Enter, Enter, down arrow, Enter.

Other systems will require other blind key combinations. Post yours here to help others.
(This will help people be able to see their Bios screens if their built in laptop panels are busted or not working. I do not know if the output selections will persist through a power off).

Coffee lake users: plug in an external monitor, close the lid and see if you can see the Bios on an external monitor automatically).