How about giving an example of such a use case, instead of just expecting me to believe that one exists?
The only valid argument I'm aware of is confidentiality. I'm not buying the argument that people have such confidentiality requirements in their private lives. Businesses can easily setup their own servers to store confidential information that WP devices can sync with. No problem.
If you are completely cut off from the internet, no wifi, no cell tower reception, nothing, then you probably have other things to worry about than synching your contact information with the cloud. Even then, it's not as if you can't access your contacts without internet access.
The "choice" argument is only valid if your are given a choice between equally sensible options. Direct P2P synching is no longer considered sensible, because it's unmanageable with more than two devices, which people also expect to work reliably.
I perceive you as rather bright and articulate. It surprises me that you can not envision such a need with out a particular example.However, I will do my best to do so. Granted, the example I have chosen may also include some of other short comings of WP8 for the business user but I hope that there is enough meat on the bone to illustrate the point. Your "valid" argument is primarily correct - Confidentiality is the key issue. However, it fails to account for the B2B aspect of confidentiality. I hope you and other readers might find this example apropos and possibly a little concerning depending on one's use model and priority it is from Microsoft themselves:
I am a vendor to the MS hardware groups worldwide. I am in front of MS Engineers, Marketeers, Program Mangers and Purchasing Agents regularly. In this capacity, I am party to a number of NDAs (non-disclosure agreements). Some of these agreements outline the control and limitation of information in the digital sense. i.e.; one of those limitations is that certain information can not be committed to the "cloud" in any form (also Sky Drive). This sometimes includes the name and contact information of some of the stake holders. P2P sync and the ability to either selectively control what goes to the cloud would sure come in handy.
One might imagine that it is highly frowned upon in Redmond to carry a non WP device around on campus and into meetings particularly for MS employees (Apples could draw a lynch mob). I have witnessed many MS folks carrying various WP devices in my meetings but have also witnessed a great majority working "double fisted" - needing to carry another smartphone to get simple work done (mostly Androids and BlackBerrys) all the while lamenting the lack of productivity, flexibility and customization of their WP8 phones and the decisions of their compatriots in the WP OS development group. - no VPN, limited email attachments, file management, poor landscape mode support, etal.. This tells me that one, MS themselves does not fully trust the cloud and two, even the most dyed in the wool, cool-aide drinking, committed MS employees can't even use their own product for anything other than a content vacuum. Further, and more concerning is that because of these limitations, some of the brightest minds at MS are "not eating their own dog food" to make the product even better.
In regard to your comment; "If you are completely cut off from the internet, no wifi, no cell tower reception, nothing, then you probably have other things to worry about"..... shows a good deal of myopia on your part, leaving me to assume that if you in fact live in the US, you must live and work either east of the Mississippi or in California. Take a gander at the North American coverage maps for all the major call carriers (particularly note the non-California West and Canada) then come back and comment again. If you are blessed enough to have ubiquitous coverage, great for you! However a good number of people live and work happily not blessed with your situation.
If truly adore a lot about WP8. I believe it has a load of upside potential. However, I look forward to the day when I don't need to work "double fisted" and can make my WP device my sole, go-to solution. The frustration is it would not be that difficult to do and still maintain the ease and elegance of the current OS.