is a backup of the previous version of the code necessary

I was discussing with my boss about the need for backups during a deployment, is it always necessary in your opinion? At my company we have lots of legacy code and the deployment looks like this. You want to deploy a app with javascript php python. You push to master then you have a pipeline that creates an artifact, deploys it to maven and the we use another manual software that deploys the app to the host and this creates a bacup of the previous content of the app keeps it on the side and deploys the new artifact. I said that sometimes you don't need to copy the currently running app folder as backup as in our case the backup is only the unbundled code with downloaded libraries and this adds complexity without benefit as you have the code in the repository. But I wanted to know is backup always a good choice in deploying apps code (not data)? Or there are cases when it's superfluous?