Tbh its the same purpose as a laugh track and I hate laugh tracks. It says “this is where the joke is”. Imo this kind of stuff helps younger people identify and parse information, especially people who are more social/extroverted.

I actually prefer doing it with typing but its because I like have a breakdown if too much sound is happening so laugh tracks use to be too distracting to me.

Imo this is more likely an auditory thing for the viewer.

Source: I have a lot of siblings and the social butterflies and kids tend to love the reaction videos, especially those who can parse noisy environments (I cannot)