Benefits of using a layered networking model

Less complex

Compared to not using a layered model, network models break the concepts into smaller parts

Multivendor interoperability

Creating products to meet the same networking standards means that computers and networking gear from multiple vendors can work in the same network

Easier to learn

Humans can more easily discuss and learn about the many details of a protocol specification

Modular Engineering

One vendor can write software that implements higher layers (like a web browser) and another vendor can write software that implements the lower layers (Microsoft's built-in) TCP/IP software in its operating systems

Easier to develop

Reduced complexity allows easier program changes and faster product development

Standard Interfaces

The standard interface definitions between each layer allow multiple vendors to create products that fill a particular role, with all the benefits of open competition.