Yes, Tilt really shines when you’re testing interactions with Kubernetes, such a APIs. But also things like your services’ ingress configuration and metrics scraping.
By default, Tilt is actually intended for local development using kind, minikube or other similar tooling. It supports developing against a multi-node cluster but it requires extra configuration and slows down iteration time.
otherwise I think it's meant for systems where system that you need for testing is to big to work on your local machine.