We Need A Separate Forum for Fuses

Obviously, modded gear would benefit similarly from aftermarket fuses.

Indeed. It would be like keeping bald tires on your car after souping up the engine.

Mercedes have been winning F1 championships with Lewis Hamilton and after market fuses. Lewis only pits for fuel, tires or after market specialty fuses. They have Bayesian computer algorithms to determine which fuses to use and when. Some fuses work well in the wet and some are better at higher altitude and some will lower the aerodynamic drag of the vehicle, others are excellent for braking. Fuses are so important  they call it F1.  

Kosst
I would agree that the number of aftermarket fuse users is indeed small, tens of thousands as you say.
However it is not in a market of tens of millions that they should be related to.
Those tens of millions are NOT high end audiophiles. That group number significantly less and dwindling every day unfortunately.
The tens of millions include appliances and applications that have no relation to high end audio at all.
Tbh I really do not know what the number of audiophiles would be worldwide, I do not believe would number tens of millions at all but I do not have that data to hand.
As far as perception of reality, I would need a few more drinks before entering that arena.