> it's the branch of mysticism of "visions" described in the "Old" Testament
The Merkabah is far more than that. It’s the vehicle used to traverse the planes and densities to put it simply. Saturn gifts it to anyone who enters his turf.

Its dormant in the vast majority of people and you have to make an effort to get it active again. Note that not that many people actually accomplish that.
The amount of people who will activate it to the point of being functional say within the next 100 years or so is extremely small.