How good would software and ml have to be before you wouldn't really need to have centralized forums? If the content of messages could be sufficiently indexed automatically- not in the sense of keyword searches but in the vein of actual comprehension- surely there are ways of doing that without anything that far from what currently exists. I don't think it would require skynet.

As someone who has only ever succeeded in bringing down the level of every discussion i have ever been in and never in contributing anything useful, it would be very helpful if i could just be automatically directed to the appropriate content sewer by posting my thoughts directly into a search engine that could dump them in the most suitable location.

Sounds like you're describing current year social media.