Trash content satisfies trash audience which makes up 95% of the audience on Youtube.. It looks like a very smart business move with zero effort.
I stumbled upon reaction videos by accident. My brother used to be married to a Filipina girl, and so she introduced us to singer Morissette Amon, who - IMO - is the greatest female singer of the last 10 years. Almost no one knows of her in the USA. She has an incredible tone to her voice, a range equal to Mariah Carey (including whistle register), incredible breath support, masterful control, etc.
After watching a few Morissette covers and songs I began getting recommendations from YouTube for reactions from people listening to her, particularly from a Vocal Coach. That interested me, since I was very impressed with her. I wanted to hear what Vocal Coach thought about her, and you can tell who knows their stuff and who doesn't by listening to them. Either their breakdown of vocal technique or by hearing them sing themselves. Or both. With Morissette being from the Philippines and unknown in the USA, it wasn't a stretch to believe that they were new to hearing her sing.
That's how I first fell into watching reaction videos. After watching the Morissette reactions I thought, "Hey, let's see if there are any people who have never seen the Stand By Me movie." That is a childhood favorite of mine, and it just occurred to me to check to see if anyone was new to that movie and had a reaction to it. The first reaction I found was by "Popcorn In Bed" reaction channel. Then I went down the rabbit hole.
Let me say this... MOST reaction channels are not believable. Easily 9 out of 10 aren't believable. I cannot watch reactions of people that can't even begin to sell themselves as watching a movie or show for the first time. For example, "KatWatchesHorrorMovies". I got only a couple of minutes in and concluded she was extremely fake. Even if she was watching a movie for the first time, she's so over the top that it was insufferable. There are some out there that are believable.
I find the ones that are most believable are foreign reaction channels. For instance, there is a channel called cinephiles where it's small village people in the Pakistan/India region. They rotate older people and younger people in and show them American movies. Almost all of their reactions require subtitles, as only 1 or 2 can speak stunted English. However, given their cultural difference I was interested to see how they reacted to things like the Exorcist.
There's also this Russian girl who moved to Canada for college and she's improving her English and doing reaction videos. She's very charming and it is believable that she's seeing American movies for the first time, especially since her earliest videos her English was much more challenged. Her reactions can be embellished from time to time, which is the worst part of her channel as she is best when she's not overdoing it, but some embellishment is understandable. If any of us watch a movie, we are not talking through the movie to the people next to us. This reaction is for an audience, so there needs to be some talking to the camera and there needs to be some embellishment of emotions. It just needs to be controlled so it's not overdone. You can't watch this girl react to Hachi, sob half the movie, and say it's not real. That movie is heartbreaking, so you know you're getting real emotions.
A greater percentage of the reaction channels that are believable are from foreign reactors. It's much harder to believe a Westerner has never seen the Matrix, for example. Most guy reaction channels aren't believable for this reason as well. I feel men watch more movies than women on average and have a wider range of genres that they watch. It is almost impossible for me to buy in on a Western man watching Iron Man for the first time. However, if you find a believable reactor that's female, I can potentially accept she hasn't seen Saving Private Ryan, even if she is a Westerner. Popcorn In Bed is one such Western girl (Canadian) who is believable in having not watched many of these movies before.
Lastly, why would I watch reaction channels? Well, most of them I do not. I can't believe them so I cannot watch them. However, if I find a real reaction to a favorite movie, I do enjoy watching that reaction because it's the closest thing to watching that favorite movie again for the first time. You witness their emotions as they go through each reveal, twist, or heartbreak that you went through that first time. I love great movies and shows, but after you've seen a favorite once, even rewatching it doesn't recapture the magic as you know exactly what's going to happen. Seeing someone else go through it for the first time brings you back closer to that first time. So there are some reactions that I do enjoy, they're just harder to come by when so many are fake beyond belief.