[A-Train]

Yes you are right it is not a very good UX. For me the most interesting part is observing the evaluations of the position from the perspective of 2 engines. See the charts that track it move by move. It is often the case that one engine sees something that other doesn't. For example, say, that it is completely busted. I imagine internal dialogue: I'm fine, I'm fine, am I in trouble... oh $^#^ I'm losing now. It was especially true in the early days of neural chess engines which saw ideas which were well beyond the event horizon of traditional engines. Most people who are watching these tournaments on twitch are chess engine developers themselves that's why interfaces like these are fine for them.