One of the key traits of a professional is the active act of abidance of a selected set of rules or guidelines while conducting business. If someone strays too much away from their ethical standards, their trustworthiness and ability to judge come into question. 

In the business world trust is everything. Because everyone is always dealing with some sort of confidential information, no company or organization will ever hire someone not trustworthy to their standards. 

In accounting sector, accountants deal with personal, sensitive and intimate financial details of individuals or organizations. A critical quality of such accountant is to take truly unbiased decisions and recommendations that benefit the client. Usually an accountant plays a very important role in many million dollar transactions. Therefore, transparency, fairness,  professionalism, honesty is expected of them. Qualities which manifest upon strong ethical belief. Strong ethical sense also helps an accountant further their career.