Because I can go to a forum that has ten years worth of information on my 6.5TD engine, over 25,000 members - people who have rebuilt a dozen of the engines, people who have towed hundreds of thousands of miles with them - and I can find the answer in a snap.
Because I can go to a SAAB forum with 42,000 members which has a dozen years of posts about my car and I can find the answer, parts numbers, and classified ads just for my car.
Because I can go to a 4x4 forum with 120,000 members - people from all over the world that have modified their trucks in every way imaginable, are building every part imaginable, and can answer any question imaginable.
I come here because it has more information about garages and shops than any of those others do - although lately there seems to be more information about what people are buying on eBay...

But I don't expect to be able to get the kinds of answers on any of my vehicles that I get at those other places because the 25,000 members are everything from old car restorers to street racers to go cart folks to truck people to....