It is analogous to evolution of how stimulated and spontaneous emission were explained microscopically in the first place:
For the case of general photon behavior, Einstein showed that the statistics of photons phenomenologically demanded that there be a stimulated process; and then (several decades later) QED provided a microscopic description of how stimulated and spontaneous processes work.
For the case of black holes, it seemed that Feynman noticed that a stimulated-like process was occurring, which (again, probably because of statistics) phenomenologically demands that there be an associated spontaneous process; and then (merely one year later) Hawking provided a microscopic description of how the spontaneous process works.
To be honest, I've never heard anyone talk about stimulated emission from black holes in the context of Hawking radiation, but perhaps it is well-known to those in the field.
Besides, isn't particle-antiparticle pair obvious, if one knows about their spontaneous appearance?
https://www.youtube.com/watch?v=7cj6oiFDEXc
Any time we accelerate, we produce a distant effective event horizon behind us! Also, "The Unruh" would make for a good name for aliens in Star Control!
Quick thought experiment: two particle-antiparticle pairs get created:
p1-ap1, p2-ap2
In regular space, after a very short amount of time p1 annihilates with ap1 and p2 with ap2. Net result is zero additional matter and energy, otherwise we'd just be creating random matter and/or energy everywhere.
If the same happens at the event horizon of a black hole and let's assume purely by chance, p1 and ap2 fall in and p2 and ap1 do not. After a short while, p1 and ap2 annihilate inside and p2 and ap1 outside. The result should be effectively the same as in the previous case, thus zero net energy and/or matter on either side. Thus, also no radiation and mass loss.
It'd be nice if an actual physicist chimed in at this point and told me where I went wrong :)
For the charge to matter, you're saying that charges infer positive or negative mass. But that's original responder's point.... both the particle and anti-particle both have positive mass regardless of their charge, which is a different attribute.
Consider how it is you are conserving energy/mass in your thought experiment. Seems like you might be creating a back door whereby that mass/energy is not conserved in order to preserve charge conservation.
The actual physicist is Richard Feynman, and here is a Feynman diagram of a particle-antiparticle annihilation.
* https://commons.wikimedia.org/wiki/File:Mutual_Annihilation_...
I agree with you about your claim, but not about your justification. I believe that "historically obvious" things ("that's the first thing I would have thought of in that situation; how did it take them so long?") are usually subject to considerable ex post facto bias.
On the other hand, when a mathematics textbook says that something is obvious, it means, or should mean: we've specifically set up the presentation to this point so that there's a unique best way to assemble the material so far, and that unique best way will accomplish the next step. This isn't always true when it's claimed, but it is possible in textbooks in a way that it isn't (or that has only a small probability) in history, since textbooks are consciously organised and history isn't.