Yeah that looks like someone that wanted to use MACD and forgot a part.
http://en.wikipedia.org/wiki/MACD
I would refrain from using that method as I have doubts that it is more efficient.
Also look at how much more responsive the MACD crossover is vs regular EMA crossover.
This bot was never attempting to implement a MACD indicator, but a simpler one using only two EMAs of different lengths (as I understand it, this is like using only the MACD line's zero crossovers as indicator).
You can read the whole analysis and discussion about this in the tread I previously referred to (Goomboo's Journal: https://bitcointalk.org/index.php?topic=60501).
I'm no expert in trading strategies and technical analysis myself, and I do not have a quantitative experience of all the many strategies that exists, but to me Goomboo seems to be a quite experienced trader, and I'm quite sure he didn't try to use MACD and simply "forgot" the signal line. His philosophy is instead: The simpler strategies tend to beat the more complex ones in the long run. Again, I can not judge whether this is a good or bad philosophy, but I like it
The signalline crossovers in MACD may very well respond faster, but it will also generate more false signals.
But of course, it would be very nice to also have MACD indicators implemented in the bot so that the users can choose.
Maybe some day