Simultaneous combat could matter if you were looking at one of your WWII books, saw that the Yamato would be at point X on such and such a day and time, crept out there and then while waiting for him to show up hear in realtime over your voice program from one of your buddies that he sank it two hours ago, 200 miles further down the line, because he did some TC that you didn't. Or even worse watching your fish about ready to impact on it and watching it slowly fade away because someone else found it somewhere completely differently due to TC. If you're not going to have the subs actually operate together without any sort of TC management code in place then you may as well play single player campaigns and post to a forum or what have you as a MP "workaround" like I believe the WaW does, or how the old B-17II groups did it.
As for playing the Pacific at 1:1 TC in MP so the game can never be shut down or saved, then the people that can pull that off are either: 1) the living definition of "idle rich" 2) Living in their parent's basements and should be getting out sometime before '43 to get a damn job or 3) probably going to get fired from their job if they go running out of a management meeting screaming "But I have to intercept the Akagi! My Computer pinged me!"...in which case you should seek serious professional help, immediately if not sooner. And better start looking for a new job to boot.
