In very short words: SF is a site for professional system administrators exclusively and we don't want non-professional questions. Low quality questions are by definition non-professional.
This is a major and important difference to most/all other sites on the SF network.
Why?
- Broken window theory. I see it every day. And unless you filter very heavily for specific tags, you just see all of SF if you are on the site often, as we don't get nearly as much traffic as SO.
- We want to attract new high quality users. That is more difficult if there is a lot of crap here.
- We don't want to read crap ourself.
- We are not the internet's help desk. Other sites exist for this.
In the end, this could be different and similar to SO, but the majority of our most active users prefer a somewhat exclusive site. This might be addat odd of how the SE network sites work in principle, but without those users, SF would be an empty shell.