I never thought that... I always thought that it's main purpose was for compositing broadcast quality analog video with digital rendered scenes from lightwave. It's second purpose was to be able to mix various analog video streams and add "transitional" effects such as crossfade, sweep, dissolve etc.
The idea being not for live broadcast, but that you put a mix together and then record it for transmission much later.
It's not like the video toaster offered anything near the quality or capability for live TV of even the most basic TV mixing desk (that every TV station would have).
This is the first time I've ever heard anyone talk about the video toaster for "live" video editing.