My default installation has a 2MB max_file_size in the PHP settings. I created an image field for a content type that allowed 2MB images.
User attempted to upload 3MB file - and received a 'Max file size limit exceeded' message and reported the problem to me.
I changed the content field size to 4MB, flushed and attempted to upload 3MB image.
I received the same error message. When I changed the max_file_size limit in PHP the error message stopped.
Since the case is detecting the image size exceeds maximum, it should be capable of differentiating between whether the failure is the field limit or the PHP limit. In turn, the message should state that the field exceeds its content definition limits or the field exceeds the system limits.
It is possible this problem also exists on files besides images, I didn't stop to look but it seems likely this also exists on file fields as well.
I considered submitting this as a feature request, but I believe it technically falls under the bug category as a use case failure. My old QA days ...:)