You're lacking in imagination, and maybe the conceptual idea of "sensor fusion". Multiple seemingly innocuous data streams in isolation can be combined to create sensors you wouldn't have imagined
Please, explain exactly what sensor fusion would get you actionable data out of the PM2.5 sensor and "gas sensor" in a Philips smart air purifier.
I mean, sure, but who is going to do that when they can... look to see when people are home.
If the burglar only takes a 30 second look before breaking in, residents could be home but away from a window, with this the burglar can more confidently know when is a good time to break in, without exposing themselves to the same risk that looking around the house brings.
It's not even far fetched, smart watches reporting physical actively at unexpected hours have revealed infidelity in the past.