There are some times an expert opinion is needed. It's the same when someone asks about being sick and people answer, "Go to the doctor." At times, our answers are not enough or the situation is too serious.
Some questions need to be clarified with a lot of details which might be impossible to list here. Plus there may not be a mechanic answering questions as any given times. Many car problems would require a mechanic to see the car, run the engine, and draw conclusions from the various sounds.
Some people just answer the questions , even if they don't know the answer so they can boost their answered numbers on ask. The tip off that they may not know the answer is when they say , check with a mechanic.