That just sends you an alert when your spend reaches certain points, it doesn’t stop you from exceeding it, and there is a one day delay while they reconcile usage.

Most people wouldn’t want to stop operating completely even if they exceed a budget so it’s really more for monitoring.

People who do want that are probably better off renting a server for a fixed cost - plenty of places still do that.

Cloud makes more sense if you are growing rapidly or have short term needs for significant increases in computing power.

At some point after that cloud stops making sense and it becomes cheaper again to host your own infrastructure.