There's always a debate about having qualifications for a particular job or an industry in general. 

Truth is, having qualifications give you a good understanding of the basics of marketing such as exploring what marketing is all about and learning textbook strategies that are applied to real life marketing situations. However, experience plays a vital role in becoming a professional marketer - it's where you can apply creative solutions to real business challenges and where you learn how to leverage new technologies.

There is no yes or no answer to this actually. It boils down to having a passion for marketing and the right attitude to progress your career.