And using things properly. Implementing a voltage regulator knowing it will fall out of regulation in normal conditions is just messy, it is obvious that it can cause unknown issues/oscillations etc, and is just as dirty/potentially bad as powering your board on an unregulated output...
I don't think we're going to be able to convince the OP that the diodes are a daft idea.
Although I do like the idea of splitting the GND line of a high current PS and inserting a diode. What could possibly go wrong.....