Benefit: A standard and purpose driven protocol for connecting agents (MCP Host/MCP Clients) to tools, resources, and prompts (MCP Server) that also exposes LLM services to said MCP Servers.
The alternative you suggest is manually integrating each set of tools or data?
Or maybe there's some misunderstanding about MCP? MCP currently has 2 transports, stdio and HTTP+SEE. The second one is, in fact, a "network-accessible API" as you call out.