Not so long ago, mastering the marketing-mix 4 Ps (then came the 7Ps), made you a decent marketer. If you also knew how to create content for the company website and manage the Facebook account, you were tops. Showing only these skills on your resume today will most likely not get you into the door of most employers.

How is it different today?

Because of the enormous impact everything internet related has had on both companies (supply side) and market behaviours (demand side) in the last decades, the optimal marketing skill sets have drastically changed for everyone including marketers. In all sectors of the economy (the primary sector being less impacted at this time), most products or services have an internet related components in their marketing mix. In the manufacturing sector, we can think of customer community assisted product design and online private markets. In retailing, e-commerce and digital marketing are omnipresent.
Today’s basic marketing skills are significantly wider-based than previously. The brain having a limit as to how much it can master, this creates more of a divide along the lines of generalists and specialists in the marketing function than ever before
In larger companies, a proliferation of new marketing functions has been observed in the last few years. Some of these functions are cross-over functions with the IT department. IT trained employees with secondary training in marketing can be as useful as marketing graduates with IT training.
Completely new marketing functions requiring statistical training and/or information systems training are also starting to appear.

What does it mean for the marketing management required skill set?

In large corporations, new marketing divisions are being created. In this context marketing management skills can be closely matched with those of the functional resources.
In mid size companies with limited resources this usually means that marketing management will need to supervise resources with a wide variety of skill sets. Marketing VPs and Directors will in turn need to train to acquire basic knowledge in the spheres where they are deficient. Managing a team without, at the very least, basic knowledge in all pertinent marketing areas will be inefficient at best and disastrous at worst.
I have also witnessed a reality; don’t have sufficient data to call it a trend, in companies of various sizes where IT engineers and information system specialists with very limited training and experience in marketing are hired to manage teams or perform high level marketing functions. This is just as bad an idea as hiring a marketer who read a few engineering books and took an engineering class or two to build a bridge. Marketing managers, now more than ever, require a deep understanding of the marketing function to ensure maximum returns on every marketing dollar invested.

Marketing skills for start-ups - Baker Marketing

How this translates to small businesses and start-ups

What is a small business or start-up owner to do in the face of such a broad spectrum of required skills to tend to the marketing function? First, accept that you will not have the resources to cover all your bases in-house. Second, get yourself the most business minded, highly marketing trained, experienced person who learns quickly and is willing to learn continuously, that you can afford, even if you can only afford them part-time. This gem will not only be able to find the right external resources to complete your marketing needs but, more importantly, will be able to create a marketing strategy that will identify the marketing tactics for your company which bring the highest ROI.
When looking at it from an investment perspective, the math becomes simple. Would you rather spend X on a lower-skilled marketing resource and receive a fraction of X in return or invest 2X on highly skilled marketing resources (internal and external) and get multiple of X in return?