Reddit was already heavily astroturfed before AI. There's no space on the internet where you can get as much bang for a buck with an influence campaign due to its centralized frontpage. The most obvious example is /r/worldnews, with millions of readers, a few thousand commenters and maybe 40k voters. To skew any discussion, you need at most 6k accounts, and that's giving you the kind of influence on American politics as would the frontpage of the NYT. You could hire real people for each account, and it would still be worth it.