It's a marketing strategy about creating the perception of;
Unique
Special
Exclusive
Reserved
Aristocratic
Fill in the blank
Back in about 1991 I actually waxed a car that I had buffed out first by machine, (rotary buffer), and then bare-hand applied two coats of M26 Liquid wax. That is I used my bare hand to apply the wax. I mostly did this to see what it was like, to see if there were any benefit to using your bare hand to apply a wax to the paint on a car.
In my opinion, for whatever that is worth... there was no benefit at all..
At least no benefit that made it better than using a normal, foam hand wax applicator pad or a foam buffing pad on a machine. I have never used my bare hand to apply a wax to a car since then and I've worked on a lot of cars. A foam wax applicator pad can absorb, in this case absorb some wax, (or a paint sealant), and then when you press on the foam just a little it will release some product enabling you to spread it out. You skin can't absorb and hold a little wax, (or paint sealant), like a quality foam applicator pad and so pressing on your skin, or pressing your skin against the paint won't release any wax or paint sealant, you have to go back to the source and get some more wax or paint sealant back onto your hand to continue spreading product.
There was one tiny benefit to applying wax with a bare hand and that was using your sense of touch if you sensed or felt any kind of particle between your hand and the paint you could stop and remove the offending particle. Not sure I've ever seen this pointed out by any other forum personality that practices bare-hand waxing? With an applicator pad you can't feel tiny particles, you have to turn your applicator pad over often and visually inspect for them and this by the way is a good habit to forum or "Best Practice" when applying any paint care product by hand or machine.
In a perfect world, the best way to apply a wax or a paint sealant to paint is without a doubt by machine, specifically a dual action polisher with a soft finishing pad or a polishing pad on the 3-4 speed setting after the paint has been previously cleaned and polished.
Spreading the pressure out
Bare Hand
When you're working with your bare hand, there's no interface to spread pressure out, just your hand against the paint.
DA Polisher
With a machine like a Dual Action Polisher, the pressure is spread out evenly over the entire face of the buffing pad assuming you're using good technique and holding the pad flat to the surface.
Wax Applicator Pad
Your hand, which is actually 4 fingers pushing down on an applicator pad creates pressure points and cannot match, let alone outperform the equal pressure applied to the entire face of a foam buffing pad with about a 6" diameter by machine.
So out of the 2 options, machine, wax applicator pad or bare hand, the machine option provides for the most even pressure when spreading out a wax, hand application offers some ability to spread out the pressure but when working by hand there's nothing to act as an interface between your hand and the paint.
A Romantic Idea
Melting wax with your hand is just a romantic idea, nothing wrong with that as it does invoke this perception of old world craftsmanship. That said, you can melt most paste waxes enough to liquefy them so the wax will flow into your applicator pad simply by spinning your applicator over the surface of the wax while it's in the can. M16 has been out since 1951 and all the old-timers knew this back in the day...
If applying wax with your bare hand sounds like a good idea simply get a clean, foam applicator pad and then do your own hands-on test and try applying and spreading out a thin, uniform coating using both methods, hand and applicator pad and then come to your own opinion and then post it here to share with others.