https://scholar.google.com/scholar?hl=en&as_sdt=0%2C22&q=red...
A point so simple it feels silly to point it out, but here we are.
The rate of spread is a problem of YouTube's own devising based on clicks, views and likes. Remove this gamification and you'll see less engagement, hence less scale of radicalization.
With youtube labeling people "radicals" is a deliberate polarising term designed to do little more than tar and feather people into a specific box. Just like segregation, just like Protestants, just like the German Jews... Etc. It's very unflattering.
https://mediabiasfactcheck.com/newsmax/
"Overall, we rate Newsmax Right Biased and Questionable based on the promotion of conspiracy theories and pseudoscience as well as numerous failed fact checks. (M. Huitsing 10/8/2017) Updated (11/12/2020)"
1. Someone who is radicalized digging deeper
2. Someone who is radicalized changing their mind
3. Someone who is not radicalized getting radicalized
#1 is bound to happen, #2 has no chance of happening, so at this point, preventing #3 is the way to go. Keeping these already radicalized people on Youtube achieves nothing. On the other hand, keeping them on Youtube gives these them a huge platform to spread misinformation. Newsmax nad OANN don't have anywhere near the reach Youtube does, especially outside the existing bubble.