Yes I would not expect anybody to spend time debugging a problem that has been resolved in a later release but I would expect people to remember there had been a problem and the solution or consider that an unresolved problem from previous release may still be present in current version. Knowledge is an accumulation, it is not lost as time and technology improves. The horse has been replaced by the car but we still know how to replace a horseshoe.
I just find it hard to believe that with all the 3.1.4 users but a year or so ago I am the only person in the world who has encountered this problem. I suspect not everybody has upgraded and there must be man 3.1 users out there.
Yes I would not be shocked to find out there are host limitations stopping multisite but should not the WordPress requirements specify what is needed. I will contact my host to ensure they provide what is required as per 3.1.4 documented specifications. But the bottom line remains the same. If you do not have latest version then support or assistance is most likely not available.