SOAP requires reading a manual before you get started, but so do the frameworks that try to replace it. APIs are APIs, you rarely need to manually access any of the endpoints unless the backend doesn’t stick to the rules (and what good do any alternatives provide if that happens?) or your language of choice somehow still lacks code generators for WSDL files.
OpenAPI/Swagger is just SOAP reincarnate. The code generators seem to be a bit more modern, but that’s about it really.