I think that‘s a bit shortsighted.
Having A2A is much more efficient and less error prone. Why would I want to spend tons of token on an AI „figuring it out“, if I can have the same effect for less using A2A? we can even train the LLMs with A2A in mind, further increasing stability and decreasing cost.
A human can also figure everything out, but if I come across a well engineered REST API with standard oauth2 , I am productive within 5 minutes.