Just report the OP, with a comment like ‘whole thread is fluffy’.
[ot]
Slightly off-topic, but unless I am being blind, the section at the front page of the forum which presented you with threads you had recently been participating in has disappeared. I know you can go to your profile to find this info, but that extra step I am certain cuts down engagement in discussions, and would be easy to get rid of again.
There is ample room for such a feature to the right of the forum listings, below the current recent posts bit.[/ot]