The main issue here is that, given it relies on whatever implementation of DBM you have installed, its performance will vary considerably from OS to OS.
I don't know how fast or slow the "dumb" implementation is, but I can bet it is way slower than gdbm. I can see someone using this module, considering it "fast enough" on GNU/Linux and then finding out that it's painfully slow on Windows and shipping binaries of another implementation is a massive PITA.
