If you play detective you can watch as people ask questions about building systems then come back and ask questions about what went wrong. In that case you can learn what to do or not do to make things work. If you seperate those from each other then members or guests will never make the connection between the two. Same for problems with software. The relation between software, hardware, and the user is best left in one spot.
As for making recomendations for this and that brand or model, it can become a sticky wicket for the forum. The members if asked about something will be more than happy to let you know what they think. Some may even be using something you're asking about.