Folder sharing broken for Business plans?

The training videos all describe how important a good folder structure is to successfully using Wrike. They promote structures similar to this:

Department
- HR
- Sales
- Dev
Client
- Client A
- Client B

Great. However, nobody from Sales has any business seeing what HR is doing. Additionally, it's often the case that people working on Client A should not be able to see activities for Client B. (Especially if the clients are competitors or if you're required to maintain the secrecy of the clients' projects, which we are.)

Apparently, because we're on the Business plan, that means we cannot benefit from any sort of folder structure at all. Every client, department, or project has to be a top-level folder, if it's to have unique sharing permissions. That's nuts.

Of course, you could pay for the Enterprise plan to get this functionality, but I think that's silly. This is very basic functionality, not an Enterprise feature. On top of that, the pre-sales material doesn't really explain this very significant limitation to the Business plan.

Does anybody else using the Business plan have a problem with this?