This is for the SME that has reached the point where marketing has to work properly, and one person can no longer make it.
The usual instinct is to hire a marketing manager. On paper it looks like the answer. In practice you are asking one salary to be a department. Done well, marketing needs a strategist to decide where to play, someone to make the content, a media buyer to spend the budget where it earns its keep, a designer to keep the work to a standard, and someone to read the analytics and report honestly on what came back. One person is rarely strong at more than two of those, so they end up drowning in the doing with no room left for the thinking. We have set out why that hire so often goes wrong here.
Now do the sums on building the real thing in-house. A manager, plus the specialists they cannot be, plus the design, plus the analytics, each a separate salary loaded with tax, pension and tools, and the media budget still sitting on top. That is a department, and a department costs far more than ten thousand a month to staff, and stands up slowly, one hire at a time. The Outsourced Marketing Team gives you that function's output from the first month, for a fraction of carrying the headcount, and none of the recruiting, managing or keeping people busy between campaigns.
So the honest comparison is not a team against a manager. It is a team's worth of roles, run for you on retainer, against a department you would have to build and carry yourself. It suits the founder or leadership team that knows marketing matters to growth, has a budget worth spending well, and would rather have the whole function run by people who have done it before than construct a department from a standing start. It fits an NGO or foundation in the same position just as well, where the job is reaching supporters and funders rather than customers, and the outreach has outgrown whoever has been holding it together.