We will change our handsets regularly from one brand to other brand but the data will be with us even you install whatsapp on new devices. It is because of your Google account. Entire whatsapp chat or media data will be auto backup to Google drive so it will ask for restore or auto restore with your drive data on new mobile without losing any message or media.
Most of the people will like to get all data but few people will not intreasted to restore total data on their whatsapp accounts for every new installs due to security or personal safety issues. That’s why I have given simple demo video of how to delete whatsapp backup from google or gmail or drive so that it will not restore your old data once you delete.