That seems like a narrow-minded and dismissive thing to say unless you know what the intended use case is. What if these IoT devices aren't just dumb sensors,

That seems like a narrow-minded and dismissive thing to say unless you know what the intended use case is. What if these IoT devices aren't just dumb sensors, and need to control some process? Then your argument is reversed; you want the data to be available locally, instead of having to contact a remote server that "will hopefully/maybe be online".