Yes, that was a no. You can try deleting your post in that thread, it might stop them.
It's not an easy change, that's why the watchlist was implemented in the first place, for this exact scenario (and adding threads without having to post in them).
I don't see what's so difficult about it, importing your current list is one click, after that it has the same functionality and usage as the "new replies" link, but has increased utility and allows you to remove specific threads.
^^^ All of this ^^^
I don't know why anyone feels the need to use 'Show new replies to your posts.' after finding out about the watchlist, it's so much better.