So, there is a limitation: hardware.
I have a mobile graphics card(r(R9 M375) (not integrated graphics) and a I7 6700HQ. Capturing data at 4K and trying to stream 4K? VERY DIFFERENT. It doesn’t have the memory to handle 4K encoding.
My machine was pegged at 90% on CPU/GPU doing 1080p, and I’m not sure how well USB2 is going to handle 4K, but it’s going to need serious hardware. That being said, records at 4K are amazing so I’m sure 4K livestreams will be as well.
I had a D&D tabletop event I was trying to live broadcast and it didn’t go well/didn’t have enough time to get OBS in line. I had to: update video drivers, update OBS, add video driver/OBS integration, update to that latest windows 10 build. There are clearly a lot of prerequisites. There was an OBS/AMD GPU plugin I had to install to enable this: