In actual fact - it's unavoidable (or should be! - but I also know it can be circumvented).
All entities (except user generated ones) do relate back to the account by default. So, if you create an activity for a contact, by inheritance, you also associated that to the account. When you complete the activity for the contact, it moves into history for that contact and, again by inheritance, also the account.
When you view history/activity by contact - you are seeing those hist/act items for that contact. But, you can roll-up to the account and see them there too. This gives you the overview of tha hist/act for that account (i.e. to see how active it is).
You can create a history/activity item for the account on its own - but not the lower level items, they always link back to account. This is by default and also to support sync (by starting at account, you can roll down and pickup data for everything that sits under it).
This is the same for tickets, opportunities - they work the same way.
Mike