Not a good excuse. There are plenty of enormous projects that provide only one basic interface to a bit of information. See every operating system API for examples.

How about the API to allocate memory in Windows?

VirtualAlloc: http://msdn.microsoft.com/en-us/library/windows/desktop/aa36...

VirtualAllocEx: http://msdn.microsoft.com/en-us/library/windows/desktop/aa36...

VirtualAllocExNuma: http://msdn.microsoft.com/en-us/library/windows/desktop/aa36...

It all started out nice and clean I'm sure, but within a few years you start to see many more than one basic interface to some things.

And {Global,Heap,Local}{,re}{Alloc,Free,Lock,Unlock}. 4 sets of APIs just to allocate memory. Although Local* and Global* are mapped to Heap for a while now and (IIRC) (un)lock functions don't do anything (but they used to). This BC is still required today.