This is working the algorithm.
tl;dr: The absolute chad who got TSC to drop their DEI initiatives... I don't want to say pioneered it, but went on the record talking about how to do it. Which is if you drop a single video with everything, even if it goes viral... you don't have any follow up. You've burned out everyone's rage in 15 minutes and then it gets lost in the shuffle and people forget and move on.
By making it an event, dropping multiple posts/videos, you keep things in the cycle longer. Because you had one video that went viral, more people see the follow up; more people see the follow up, means the original video stays ranked higher for longer - which means ever more people see the follow up video, and then the Follow-up to the follow up is ranked very high when its released.
You also keep people angry/shocked/offended. Instead of one blow where you max out their feelings, you keep them exposed and now they are angry, for longer, and not ever hitting their limit. They are also TALKING about. Speculating what will be in the next video, etc, boosting the engagement (and thus its place in the algorithm) even further vs. a one-and-done megavideo.
Additionally, as another poster said above, it keeps Mr. Beast from dropping a single "Me so sowwy" video. You can make a "I made a fucky-wucky guys. I've changed though, Please keep streaming and buying my shitty over-priced burgers" video once. After the second or third video, this no longer seems like a single one-off event and starts to ring hollow. The point is that this stuff is about a pattern of shitty behavior, and so by making a video about each scandal, it demonstrates said pattern.
It also gives a chance for more whistleblowers to come forward. You might have a pretty good killshot, but there's nothing wrong with getting more ammunition when you go after the king.
I think we can all agree the preference would be for a single omnibus "This is how fucked up Mr. Beast is" video, but that's not conducive to actually achieving the aim of showing people how much of a gooning asshat he is.