DTL, diode-transisor logic, was used in 1960-1970's when they did not have cheap high-quality transistors yet. The power consumption was pretty terrible, but you needed less semiconductors.
In the modern logic, diodes are not that useful because transistors already react to one polarity only. You simply connect multiple transistors to same input, and the right ones will activate.
In the modern logic, diodes are not that useful because transistors already react to one polarity only. You simply connect multiple transistors to same input, and the right ones will activate.