The LJ FAQ has this to say about the subject:
When there are at least 50 comments on a page, the comment threads
will collapse, so lower-level child comments display as a link rather
than the full comment. This automatic behavior can neither be prevented
nor triggered sooner.
I'd like to post this to a community where users discuss what they want to see improved in future LJ development, but I don't know of such a community. I could file a support request, but I don't actually want support -- I know there is no solution to my problem short of changing how LJ works. And I have filed a support request on this in the past; the interface to do so was a pain and the response I got was less than satisfying. I don't want to talk to the LJ staff directly, I want to talk to other users in the hope of getting a groundswell of customers saying that this needs to be changed, because while it's clear that they won't listen to me alone, they would listen to a large enough mob.
So, if you read cadhla, filkertom, or any other pages that get lots of attention and comments, and you read the comments, and you don't like how you suddenly can't see the comments on comments when the 50th one gets posted, speak up. Post about it on your own journal.