What an in-house hire offers that an agency usually cannot
Someone embedded in the business day to day builds a depth of institutional knowledge about the product, the team, and the customers that takes an outside agency real time to replicate. For a business whose content depends heavily on that first-hand knowledge, in-house tends to be the stronger fit.
What an agency offers that a single in-house hire usually cannot
An agency brings experience across many accounts and platforms, plus a built-in team covering roles a single in-house hire cannot: strategy, design, video, reporting. For a business that needs broad capability without hiring a full team, an agency tends to be the more practical fit.
A reasonable way to decide
If the content strategy depends heavily on first-hand knowledge of the business, in-house tends to serve better. If the priority is broad capability across many skills without building a full internal team, an agency tends to serve better. Some businesses land on a hybrid: an in-house hire handling day-to-day content, with an agency brought in for specific campaigns or capabilities.