It is all event driven
Just as you cannot imagine any modern application to implement a single-threaded synchronous processing model, same applies to any modern distributed system - you should design them with asynchrony in mind.
After all, from the earliest Windows graphical user interfaces, to network systems composing of hundreds of microservices - every model that scales both in maintenance and performance is event driven. Therefore, moderm architecture should all push for systems with asynchrony driven by designg system's architectures with event driven systems right from the beginning.
As much as asynchronous model may differ from the simplest traditional implementation, implementing asynchrony at the systems' core later on is extremaly expensive, if not impossible in business terms.