So now you have 2 machines talking to each other in text-to-speech English over audio, then having to do speech-to-text on each others audio streams, and then natural language processing to understand the message etc.
When all we needed instead was a simple API endpoint over the internet for the business where a machine could talk to the other machine with just a few bytes of information to convey the same information and process the same transaction.
Instead we are wasting bandwidth and tons of cpu cycles and electricity making the machines emulate a human analog conversation.