I recently had a interesting discussion with a user regarding his particular heatsinking issues attached to an answer I gave here.
However, since then, Kortuk♦ has come by and stated:
@FakeName Can you message me when you add applicable information to your post and I can clear these comments? Otherwise I will just purge in a day or two.
Now, I understand (if not agree with) the desire to clear out comments that are clearly unconstructive. However, in this case, the comments were clearly illustrative of the process of choosing the appropriate heat-sink solution, while beeing somewhat too localized to be part of the answer itself.
I cannot see any good reason to delete these comments. They're both informative and amicable. I think that the knee-jerk deletion of any comment threads longer then ~5 comments is an absolute anathema to a proper educational, open discussion.
Frankly, the process of designing things is as or more crucial then the parts involved, and it is very difficult to illustrate the process without at least some back and forth. If you want to claim that trying to illustrate the process of designing something, particularly in the context of walking someone through the design process is not a good fit to the SE format, that's fine. Then close the question.
Otherwise, the deletion of useful, informative comment discussions is absolutely toxic, and should be discouraged.