There've always been (a majority of) broadcasters that had seconds to half minute (!) delays. Very few understood, or even today understand, how to tune every single touchpoint (including what's safe to do, and what one must not do.)
Having an ultra low latency “video toaster” / broadcast mixer is a critical piece for sure.
For us the motivations to work on this started with "backstage feeds" synced with live TV that needed to look simultaneous to the home cable viewer (think World Wrestling Entertainment) as well as Wall Street calls that needed to be (perceptually) in sync with dial-ins. And of course, Times Square NYE ball drops!
In reality, almost nothing matters that way. For vast majority of content, the viewer is consuming only your stream, without some more real time channel at the same time. In most cases, the viewer cares far more about visual quality than the delay.