So some possible reasons:
- Success: all the basic questions were answered, and the complex questions are hard to ask.
- Ownership: In its heyday, projects used SoF for their support channel because it meant they don't have to answer twice. Now projects prefer to isolate dependencies to github and not lose control over messaging to over-eager users.
- Incentives: Good SoF karma was a distinguishing feature in employment searches. Now it wouldn't make a difference, and is viewed as being too easy to scam
- Demand: Fewer new projects. We're past the days of Javascript and devops churn.
- Community: tight job markets make people less community-oriented
Some non-reasons:
- Competition (aside from AI at the end): SoF pretty much killed the competition in that niche (kind of like craigslist).