In the end it was JSON plus API description and generation tooling that delivered, though XML lives on under the hood in lots of places. It’s usually used for cases closer to markup like word processor documents or for very complex configuration files.
Hype is just something you have to get used to in this industry. It’s really bad. Any new thing usually gives birth to a wave of breathless unhinged hype whose main purpose is to get corporate purchasers and VCs to cough up money.
XML has schemas and validation as part of the main standard. JSON still doesn't have that. There are some things tacked on that 90% of people don't use.
XML has comments, JSON doesn't (!).
JSON is okish and it's easy to pick up. As Visual Basic, Javascript, PHP, Ruby, Python, Golang have proved, convenience at the start beats almost everything else.