Connecting technology at home to your Wi-Fi network (and each other) has several benefits. The first is control and convenience. You can control everything in real time, either from an app on your smartphone or tablet, or from a voice-controlled smart speaker.
Secondly, there is information. Smart home gadgets can give you easily accessible data on issues such as security - say, access to a history of smart security camera flows - to smart energy meters and power monitors that tell you (and the provider utilities) go through that.
The third is automation. If you do not want to manually control your home gadgets, you can go further and set scenes, routines and rules.
Depending on things like entering / leaving the house / apartment or sensors that are triggered, you can set certain actions as a result. The idea is that your home knows you and your family / friends and works automatically based on what is happening, without needing your input.