Marketing is the front face of a company which leads to brand recognition and customer buying tendency. These days most of the company is thinking of cost benefit strategies especially investing to have inhouse agency or  outsource it. They are big media agencies in the market who are expert in creating the advertisement but they charge heavily while the inhouse marketer where's different hats to execute the task. Cost, productivity, area of expertize etc are some factors on which the company decides where to invest.

Read more at: https://www.business2community.com/marketing/who-should-you-hire-first-marketer-or-agency-02189024