>>98491060No one really knows, maybe some legal issues where the "character" can only be voiced by their respective talents?
I remember when Haachama did a stream on her channel using Kanata's model and she got in trouble because of it.
Council somehow got permission to do it for their first April's Fools stream but wasn't given the permissions to do it again.
But again there were some cases where they're allowed to do it on 3D streams like when Pekora had other talents use her 3D model on her 3D anniversary stream.