This is kinda Frodo Friday workouts, he incorporates instagram live some of the time and answers Q's/interacts loads in the chat. However, for free riding on zwift you are 100% correct in that when free riding (which I do quite rarely as I'm normally racing or doing workouts or group rides) you get limited interaction. That said the zwift livestreaming scene is growing, for example Ed Laverack does great videos and livestreams with interaction and loads of training advice whilst doing group rides, sessions or races, and that contributes a large part to his living (alongside his partner working)
if a top level triathlete were to do that sort of thing it would no doubt be a good opportunity to grow as a brand (but also would be difficult to fit in around training/life etc if your not wanting to fully commit to it as part of what you do... and if you don't like sharing your numbers definitely not something to do)