They do make some tasks tricky to handle, like tracking state, or avoiding race conditions, but in reality events are a good fit for interacting with browser DOM events, representing browser activity, and being able to react to it.
Consider the complexity of an average modern web site, that loads dozens of scripts, uses a frontend framework, is highly dynamic and interactive (likely a SPA), contains multiple frames, etc. All of this happens concurrently, and the only abstraction that makes sense to represent it is an event-based system. You can't achieve the same level of responsiveness using a traditional request/response protocol.
This is why modern browser automation protocols are event-based, and built on top of WebSocket. Selenium is pushing for WebDriver BiDi, while the browser standard is the Chrome DevTools Protocol.
They do make some tasks tricky to handle, like tracking state, or avoiding race conditions, but in reality events are a good fit for interacting with browser DOM events, representing browser activity, and being able to react to it.
Consider the complexity of an average modern web site, that loads dozens of scripts, uses a frontend framework, is highly dynamic and interactive (likely a SPA), contains multiple frames, etc. All of this happens concurrently, and the only abstraction that makes sense to represent it is an event-based system. You can't achieve the same level of responsiveness using a traditional request/response protocol.
This is why modern browser automation protocols are event-based, and built on top of WebSocket. Selenium is pushing for WebDriver BiDi, while the browser standard is the Chrome DevTools Protocol.