I'm Sick of These Threads
I have a suggestion for you or anyone else who doesn't like to see the threads they are no longer interested in jumping to the top of the list of threads on their profile page.
Right above the topics, there is a toggle that allows you to switch from "recent activity" (which is triggered by anyone who posts in a thread and is the reason why old threads you aren't interested in keep jumping to the top) and "my post date" (which lists the thread topics by when you last participated.)
If you toggle to the latter, then threads you are no longer participating in no longer jump to the top of the list of topics. Basically, it changes the list to your most recent interests, not the most recent interests of other posters.
Give it a shot. It's not a perfect solution, but it might work for you.