The importance of an organisation really depends upon the size of a business. A very small business is much less likely to depend upon the structure of an organisation for success than a large business.
I've outlined some of the reasons for this alongside the benefits of an organisation below.
Small businesses and the importance of an organisation
What's known as a "tall organisation" works on the basis that a large number of employees have a variety of individual roles. Each individual can report to someone higher within the organisation.
The significant factor that reduces the importance of a tall organisation within smaller businesses is the fact that employees will often have a variety of different roles to perform on a daily basis, and will commonly report directly to the owner of the business.
In this instance, there is much less need for an organisational structure, as communication between employees and the owner is much less complicated. There is no confusion about individual employee's roles.
Larger businesses and the importance of an organisation
It would be very difficult for an owner of a business with 1000 employees to know at all times which particular employee was responsible for each business task. In this case, employees would report to their department manager, who would then convey that message to either a manager above them, or directly the the owner.
What this ensures is that communication isn't misinterpreted or lost, and enables the performance of different departments to be analysed individually.