Is this necessary or desirable now? I've noticed a reluctance on the parts of moderators to close threads with 100+ posts lately (either due to a wavering faith or because the new babble's beta-testing demands so much of their time), so perhaps its time to revisit this aging babble theme.
As far as I remember, our reasons for closing threads in the old babble were 1) sympathy for dialups and 2) killing off of threads that had outlived their usefulness.
Surely with the new babble and its attendant bandwidth demands we can discard the pretence of concern for the broadband impaired.
So the only question becomes 2), and I'm not sure this is enough on its own. For one, reaction threads like 'Reporting Tech issues to rabble & sons' don't seem to benefit from arbitrary closing, since they really benefit from continuity and repeat questions pop up despite having been dealt with on earlier incarnations (although, I realize that this will likely happen anyway, with about the same frequency, even with spooling threads, but it's the goddamn princible, man).
Secondly, archive threads like 'Still losing the war' and 'All hail the Israeli Resistance' that have a rich history would surely benefit from consolidation--and closing them doesn't serve much purpose (does it?) because it will only be a matter of minutes before another babbler starts a new thread--sometimes with added confusion like a different thread title on the same topic or without a link to the previous thread. There are countless threads that are closed in the name of this convention, and I'm not sure that that's a positive thing.
Finally, there is little doubt that many threads do benefit from being closed without a word of judgement as to why: threads on religion or Islamophobia come to mind. jrose or bcg pop in to a particularly toxic thread with a cheerful 'long thread!' and all is forgotten and forgiven. Well, not really, but you get the idea. So I realize that if thread spooling is re-introduced (remember when we used to have it?) this will take away a valuable moderating tool, and perhaps that's enough to warrant this old canard's continued existence.
Nevertheless, it seems like even the moderators are questioning their faith in the ol' thread length shibboleth of babble, so perhaps we should reopen its dicussion?