IT services companies have become more and more common over the last decade or so as the ability to work effectively remotely has become easier.  Many business owners and management professionals are not familiar with these companies and what they offer, or may not understand the benefits of hiring such a company.  These companies offer, essentially, an outsourced IT department, backed by standardized policies, procedures, and technology.

Speed

One of the biggest benefits of working with such a company is that it can lead to a fully functional IT department in a relatively short time.  Hiring, procurement, testing, training and the like are simply skipped.  Because these companies work with so many different businesses, going from contract to being up and running quickly is something that is both very important to them and something they have practiced and have quite a bit of experience with.  Adding services, technologies, or positions is much easier with this setup, both because the IT services company is more familiar with the requirements of spinning up a new service and likely has most common services ready to go, but also because they are focused on these specific types of problems.  They are the experts in the IT field and lessen the research and understanding required from upper management before starting these projects, as they can be experienced guides.

Cost

Most of these companies offer some kind of subscription or planned cost model, depending on the clients' needs, this can actually save quite a bit of money.  Hiring the IT employees, providing hardware and software, providing training, and even offices and seating are all business costs that can be skipped by use of such a service.  The services company can take advantage of economies of scale to provide round the clock coverage, particularly skilled experts, and monitoring services that might cost quite a bit to have on hand.  If the client is only paying for services used, this can be particularly impactful for small businesses, where IT support is intermittent and occasional.

Flexibility

An IT services company can have a deep bench of talent and apply it as necessary, from implementation experts to technicians experienced in rare or uncommon technologies.  With the working coming in from many clients, they can keep these employees busy on projects where having such an employee on staff would likely lead to them being underutilized in many cases.  This ability to flex to implement new technologies or handle higher volume and then back down can be invaluable.