If you are a minor and your parents have Family sharing turned on then they benefit as they can see you are mostly playing games. If this is a work phone, i.e., either your work provided it or you use it for work and it is a managed device this benefits your employer as they want you to be working with their device.
If this is your device and only you have access to it then no one else can see what you are doing so I don't see what the issue is then. It is very helpful if a user has a battery malfunction and something is draining their battery to see what it is and to take appropriate action. It can also help Apple techs if they are diagnosing a phone.
No, Apple does not collect your battery usage and can only see it if you give them permission, such as getting your phone serviced. It makes no sense to turn off battery usage information, it can be very valuable. It is not a privacy issue or a software coding issue.