Airbnb does not, in fact, have a CTO who dictates the company tech governance and/or stack. They prefer to run things in a federated manner, with individual teams making the decisions that they feel are best for them. While they're encouraged/required to draw up design docs and have them reviewed by an architecture review group, the group's recommendations are non-binding.
This model has advantages and disadvantages. On the upside, it creates an environment where people can take risks and do things that haven't been done inside of the company before. On the other hand, it means people sometimes go out on a limb and push the company into supporting something that turns out not to be sustainable in the long term.
As a matter of personal preference, I like to have a set toolchain that a company is built around. But it would be unwise to suggest that Airbnb's strategy hasn't worked out pretty well for them overall.