That could indicate that the thread had a medium relevance for a wide range of people, not a high relevance for a specific set of people. SO seems to focus on the second.
I think they fear a slippery slope to becoming /r/programming with everyones favorite cartoons, favorite quotes and "what do you hate about php?"-questions on the front page.
The site fell pretty far down that slope in its first year before turning itself around. Here are some good examples of top-30 questions from the days of softer moderation:
- What's your favorite "programmer" cartoon?
- What is your best programmer joke?
- Great programming quotes
- Defend PHP; convince me it isn't horrible
- What is the best comment in source code you have ever encountered?
- What's your most controversial programming opinion?
- What are some funny loading statements to keep users amused?
- Worst UI You've Ever Used