Me neither.
This is my theory.....
Capacitive supplies are mostly used for low power, which were traditionally served by small iron-core transformers.
But iron-core transformers have been mostly superseded by switchmode power supplies, and the manufacturers have stopped producing the smaller size magnetic steel lamination, and thus the small transformers have either become unavailable or expensive.
Unfortunately, for an electronics novice a mains-powered SMPS is beyond the reach of their technical capabilities. Therefore, they consider capacitive power supplies.
But, they attempt to extrapolate those circuits into multi-watt supplies, powering all sorts of stuff, and that is where the problems begin.