I will never say that exam can not be cleared without the coaching there are many examples where people have achieved this fate. But coaching is good if you want guidance and want to have consistency with your studies. Now days even online coaching facility is available to save your time.
Ranking is the most important factor. No ranking means no business. Lets suppose I have an institute and provide online tutors. If my website is not in first page when someone is looking for online tutors then I will not be able to make any growth. Therefore ranking is an important factor.