Alternative to easy-driver (or adafruit motor shield ) on breadboard
The L293D and similar H-bridges are essentially dumb current switching drivers, not stepper controllers: When the ENable pin is high, the A pin input determines whether the corresponding Y pin output is high or low. 

In order to implement a 2-input STEP / DIR control, a layer of logic glue is needed, to translate those two control inputs into suitable coil energization signals to be fed into the L293D.

The logic layer needs to not just control a sequence of values for the A pins, but also be aware of stepper position, especially to implement micro-stepping. An application like a CNC is best implemented via micro-stepping, to avoid big jerky steps or a huge gear reduction ratio.

Further, to cope with a variable load on the stepper and yet provide sufficient and consistent step torque, a current-sensing chopper drive is required. 

Getting all of those pieces working on a breadboard without using a motor controller or a dedicated microcontroller is a pretty massive task, and would end up costing significantly more than just using a stepper motor controller IC, or at least, as illustrated in one of the instructables mentioned in the question, a dedicated microcontroller.

Finally, depending on the specific stepper motor being used, the current required for driving it will probably far exceed the breadboard's current ratings - A breadboard is not designed to support several amperes of current, even in short bursts. A melted puddle of plastic and metal is a likely outcome.



The reason motor controller ICs such as the A3967 and the Texas Instruments DRV8825 exist is to simplify stepper motor control, current control / chopping, and microstepping. The two driver modules mentioned in the question use those controllers. Other stepper controller modules, such as the StepStick, exist as well. 

These controllers typically cost less than US$4 on eBay (1), (2), making it highly unlikely that a breadboard stepper driver could come close in cost or capability. 



Here is a trivial solution specifically addressing breadboarded stepper controllers: 

Obtain a stepper motor controller IC such as the DRV8825, solder it onto a SMD to DIP conversion PCB, plug that PCB into the breadboard, and hook the stepper motor up to this. The support components needed by the motor controller IC can go on the breadboard, other than any parts in a high current path. For those, just hook them up lead to lead, well off the breadboard.