Good question I suppose in need of clarification. Regardless I think not being able to comment or report an observation in a thread you're seeing a certain pattern on is problematic, and suppresses conversation of otherwise legitimate observations and concerns; where better to discuss an issue than where observations are being made?
I think the rule being put in place was because it was happening so much, which should be seen as a strong signal that there is a problem. But rather than fixing the problem or attempting to perhaps through experimentation, it's suppressed as much as possible so then the conservative status quo can continue at whatever externalized costs the people bringing it up have.
E.g. We should all know by now there are bad actors out there, even individual people, who maybe develop a grudge against a single user - and are more likely technically skilled enough to create and maintain a handful fo "real user" accounts on HN that would go undetected with whatever (if there are any) measures may be in place - who then may target one specific user; or industrial complexes who may have bot nets of 1000s or even 10,000s (or more) users to go relatively undetected, who then suppress certain types of comments if certain topics are mentioned, etc.