- you are thinking about a company doing good things the right way. You are thinking about a company abiding by the law, storing data on its own server, having good practices, etc.
The moment a company starts to do dubious stuff then good practices start to go out the window. People write email with cryptic analogies, people start deleting emails, ... then as the circumvention become more numerous and complex, there needs to still be a trail in order to remain understandable. That trail will be in written form somehow and that must be hidden. It might be paper, it might be shadow IT but the point is that if you are not just forgetting to keep track of coffee pods at the social corner, you will leave traces.
So yes, raids do make sense BECAUSE it's about recurring complex activities that are just too hard to keep in the mind of one single individual over long periods of time.
1) Even when you move things to a server, or remove it from your device, evidence is still left over without your knowledge sometimes.
2) Evidence of data destruction, is in itself as the name implies, evidence. And it can be used to prove things.
For example, an ext4 journal or NTFS USN $J journal entry that shows "grok_version_2.4_schema.json" where twitter is claiming grok version 2.4 was never deployed in France/UK is important. That's why tools like shred and SDelete rename files before destroying them. But even then, when those tools rename and destroy files, it stands out, it might even be worse because investigators can speculate more. It might corroborate some other piece of evidence (e.g.: sdelete's prefetch entry on windows, or download history from a browser for the same tool), and that might be a more serious charge (obstruction of justice in the US).