Ah Giok, you beat me to it while I was composing a post. Tracing would seem to be the obvious solution if you are losing threads.
However, they don't disappear faster because there are more threads. They might get lost in the crowd (which is why you should trace them), but, despite what some people have said, extra threads can't push other more interesting threads off the bottom, because the page shows threads posted to for the last 24 hours, no matter how many there are. A few extra threads would make the list a bit longer, that's all - your more favoured threads won't disappear until they haven't been posted to for 24 hours - which I suppose might happen if people found the copycat threads so interesting that they posted to them instead of the ones you like.
Personally, I don't see the problem. I trace the threads I want to follow, and even if I've been away a few days and need to set the filter to 3 or 7 days or whatever, I don't have a problem finding them. Actually, I think some of the copycat threads turn out quite funny. There is often the potential for witty repartee and interesting thread drift because they are open to all kinds of interpretation. It's good to lighten up sometimes.
Actually, when I started to read Susan's post, I thought she was saying that since we don't all like the same things, we could just pick and choose what we want and ignore the threads we don't like, and I was all set to agree with her. But her point turned out to be quite different. I suppose if you are on dialup AND Mudcat is running slow AND you didn't trace the threads you liked AND you don't like the copycat threads AND you've missed a few days, AND AND AND......it would be somewhat more inconvenient to have to check out all those nasty new frivolous threads.
The threads I am much more likely to avoid are the ones with endless political rants and long cut and pastes. Doesn't take much creativity to cut and paste. I could get annoyed that they are cluttering up the BS section, and I have even occasionally opened up new threads that I thought might be interesting, going by their title, only to find that they are either boring, or full of rants and personal attacks etc, and I just decide not to look at them again. I don't resent the fact that they are there. Somebody obviously enjoys them - they just aren't for me, that's all. It's called Diversity!
So - trace the threads you like and leave the others alone. There's room for all tastes here, IMO.