Baloney -- for the most part
Gene, as far as grounding the outputs go, DON'T. If the inputs naturally assume a state that forces an output to a HIGH, bad things will happen. It may be that the instructions were to ground unused INPUTS vs. outputs. The idea there is that it keeps the current draw a little lower.
Decoupling each +V pin with a massive cap like that is pointless. However, I feel that decoupling is one of the most important -- and neglected -- things that you can do. It's even more neglected when breadboarding circuits and a lot of circuit problems can be avoided if you use proper decoupling. But most decoupling problems, especially with digital circuits, have to do with higher frequencies, and the fat electrolytics don't deal with those well at all. Yes, decouple each +V pin, but do it with a 0.1µF or 0.01µF disc ceramic cap from +V to ground, one cap for each chip. The disc ceramic caps are better able to take care of those fast transients that get into the supply lines and cause false clocking or false resets and such with clocked logic.
If working with analog circuits, I prefer to decouple each +V and -V (if a negative supply and not ground) with a 10µF aluminum or tantalum electrolytic cap in parallel with a 0.1µF or 0.01µF disc ceramic cap.
Dean