Currently not every building's WiFi is accessible to you. Second, WiFi only has a limited range. If your house is at the edge of settlement for example and you

Currently not every building's WiFi is accessible to you. Second, WiFi only has a limited range. If your house is at the edge of settlement for example and you take a walk in nature (or just the nearest park!), you won't get any WiFi after the first dozen meters. That area may very well be covered by cellular though. Cellular has a much higher range and will still be very important.