Many of these recommendations - like many JVM argument recommendations - are old. Even the quite old recommendation of setting the minimum and maximum heap size is not necessarily a performance enhancer from what I've read on the intertubes. Though one does have to set the max heap size if one wants it to be able to get bigger than the built in default.
Ideally one sets these by testing and tuning, but obviously many people/sites don't have the time to do much in the way of this and the JVM has quite a few possible arguments and often little or no explanation of their function. At this point, with java 8 I'm setting fewer arguments and letting it determine what to do as much as possible which has worked surprisingly well. The G1C1 GC seems to work well on the sites I've seen with it.
