It's not a theory.
netsh winsock reset kicks out any installed LSPs and resets the system to those that were "being delivered" by the Windows OS you have installed.
In MY case, it's "only" the DSL manager software I have installed - and wouldn't like to lose.
At least that's the most obvious thing I've found - there might be others gone I'm not yet aware of, but since it's a system that was set up only recently there isn't too much stuff on it yet.
If there wasn't any third party LSPs installed on your system, iTunes shouldn't have had a problem accessing its store - so you can bet your system is currently missing some functionality.
You can test it for yourself - reset your system back to the state before by a system restore (if that's still possible, that is), do a "netsh winsock show catalog > before.txt" to capture the current list of LSPs, then do a netsh winsock reset and capture the current state again with "netsh winsock show catalog > after.txt".
Then compare the files with a tool like DiffMerge or similar.
In my case, the list shrunk to about one 4th of its previous size.
Google for some more in-depth details about LSPs. It would bust the forum a bit.