IT has become very broad in the last few decades and virtually no company can handle all areas of the market. In most cases, companies that are not strictly specialized in IT infrastructure need not necessarily have knowledge of it.
Additionally, building in-house data centres is a burden for most IT companies, especially if it is intended to meet the prescribed and anticipated security and accessibility standards.
On the other hand, the purchase of IT services through licenses and maintenance is in decline because customers prefer paying by user or traffic, in the form of SaaS Cloud. In this way, they achieve a high level of service and avoid certification for those parts of the business for which the data centre is certified.
The data centre does not develop applications and cannot compete with classic IT companies, which makes it a natural partner to IT professionals. In addition to facilitating IT companies by helping to deliver their services through data centre infrastructure, that otherwise would not be possible, IT companies often participate in projects concerning third parties, thus gaining additional sales.