That would be harder to implement and would require more clicks by the user, I suppose. I only want a quick and dirty way to follow someone through the discussion without hiding other people's posts. Of course you may have other ideas, but I only wanted to make clear that I think that the feature would grow too big compared to the simple concept I have in mind.
Once again: It could work this way but then it would change the way the thread is displayed. My idea was just a link to jump through it.