There are two reasons.
1. Sharing opinions with other people can give you more than simple research in the internet, everyone has his own experiences so in my opinion it can be helpful. This website is perfect for it. at the momment.
2. Visiting the Discussion board is in my opinion the best way to find the best eventual exchange partner or teacher or tutor. There are a lot of people here who aren't active cause they were here once in a lifetime but Discussion board are the best way to find experienced intelligent people who are active here so you can be allmost sure that they could help you in learning a new things. A lot of values.
The people that are asking these questions might not have a lot of faith into Google's search algorithm. I've had instances where Google gives me something i wasn't even searching for (e.g. the game Kotor when i was searching for the city of Kotor).