I saw it in From Other Suns a bit. People would do this and then block with the Shield which made you invulnerable due to the fact that the shield is bigger than your head, and the floor stops the bullets from hitting your burrowed body.
Then two weekends ago there was some Mech Fighting game that had a free weekend. I jumped in, and it is pure Multiplayer. The people I fought against always started the match by burrowing. I had to punch the ground trying to hit their head while their hands did max damage to my body.
VR may not be ready for Multiplayer Fighting until Game Developers properly code their software to prevent this type of Cheese.
No idea (yet) if Multiplayer is cross-platform. The game is available for OH, Steam, and PlayStationVR.Cross-Platform competition across all 3 of these would be badass!