Rel Does Not Recomment Isolation Stands

This doesnt surprise me one bit. In just about every situation, especially involving speakers, it is a question of what is be done with the energy. At first glance it would seem to me that you should drain this energy, but some disagree. 

The think the real issue is what type of floor is present in your listening room, I have a dedicated room with wool carpet over concrete and I can see no reason in this case to do anything other than drain the energy by coupling. 

I can think of any number of reasons why you wouldnt want a speaker (sub or not) moving even the tiniest bit in space. What happens to the energy when you put a speaker on springs? Or is it like the Harbeth theory that the energy is drained through the vibration of the cabinet? A theory which to me makes absolutely no sense.

Yeah I would tend to listen to the manufacturer rather than take the advice of hobbyists myself included. There is no one size fits all in this game and the requirements of a speaker are very different than that of a turntable. Take REL's advice. 

There are actually people who dont live in houses?

Things will vibrate regardless of weight. Worst possible scenario is a speaker with thin walls that vibrates. What do you think the cabinet does when it vibrates?