As they say, you can't un-ring a bell. Once someone has seen a file, it could be in their browser cache, they could have saved it, and they might just remember its contents.
This no more prohibits revocation than right-click traps do. It was impossible to stop to begin with.
(Of course, I think you understand this, as you mentioned the browser cache. I'm mentioning this mostly for the benefit of later readers)
Comments
It does have the important disadvantage that you can not revoke access to anything. If someone has seen it once, they can see it again.
On the other hand, who cares... it's also in their browser cache
As they say, you can't un-ring a bell. Once someone has seen a file, it could be in their browser cache, they could have saved it, and they might just remember its contents.
This no more prohibits revocation than right-click traps do. It was impossible to stop to begin with.
(Of course, I think you understand this, as you mentioned the browser cache. I'm mentioning this mostly for the benefit of later readers)