Postman is just a terrible GUI for making HTTP requests. Using a REST API can be as simple as `curl https://api.github.com/repos/torvalds/linux`, and you can even open that link in a browser. SOAP requires sending a ton of XML [0] - it is not very usable without a dedicated SOAP-aware tool.

[0] https://en.wikipedia.org/wiki/SOAP#Example_message_(encapsul...