As long as they don't try to stop custom songs I suppose I don't have a major issue with this even if I'm disappointed to see it.
In the grand scheme of things Facebook's reach and resources greatly outreach beat sabers so they could potentially set up lots of music contracts far faster to get a steady stream of DLC on all platforms.
On the flip side this means I won't be buying all the DLC just to support the company, I will be far more selective with what I get now.
Either way I already got beat saber on the PC as well in case I eventually can't put custom songs on the quest. There were some things I wanted to mess around once I got my new computer and the link working in general.
Chronos, Lucky's Tale, Edge of Nowhere (Insomniac made game, $10 just today on Oculus store), the new GTA V mod, Elite: Dangerous, No Man's Sky, I Expect You to Die, Euro and American Truck Simulator games, Dirt Rally, SkyrimVR and Fallout 4 VR (with snap turning), Moss, Alien Isolation (Mother mod), Vivecraft (you can use m+kb in addition to motion controls for this).
That should get you started :)
Thumper isn't a bad VR addition either as while it uses a traditional controller the visuals still look neat in VR.