YSK long noise videos cant effectively be compressed and as such take quite a lot of storage space and bandwidth. So if you want to keep the hosting costs of social media platforms low, for example when going public, you definetly wouldnt want disenfranchised users to upload them to your platform. This is the kind of noise you would want to avoid: https://stackoverflow.com/questions/15792105/simulating-tv-noise#15795112
If it’s VBR, either two things can happen, the compression esteems the noise can be averaged to a solid gray background, and the bit rate will be very low to just display a solid gray card, or it deems each pixel worthy of staying distinct, which forces the compression to drop and will raise the bit rate to the maximum.