A fuse, but it's very nature, by it's very design parameters...exhibits some very well known "in-harmonic/non-linearity", or odd ordered distortions... when exposed to dynamic signal flow.
DC or ac application of a fuse in the world of audio means it is subject to having signal modulated though it, in almost every single case of use. Except that of lets say a DC output power supply into another dc circuit. Minimized flow changes.... but there may still be some residual modulation in the throughput of the given fuse, if it is hooked up to a circuit which modulates draw..as... Audio = inconstant dynamic ac signal.
The human ear is quite sensitive to the sort of non complementary distortion signals that a fuse contributes to the signal it is being modulated by.
Again, all of which (the fuse behaviour) is well known in the fuse business and associated science and engineering.
We do know the ear is inordinately sensitive to those odd ordered distortions.
Thus removing a fuse from a circuit is the biggest level of gain we can 'hear', in the given fusing situation (installing a conducting wire jumper/bypass, etc).
Altering the given in-situ fuse in one way or another may change those complex inharmonic signal modulations, which humans will, from all evidence shown..very likely hear as changes in the given signal.
No mystery.
Directional aspects are apparently the issue being debated at this time. A little more difficult to illustrate, within the confines of expected science and engineering, with respect to the average reader's education and scope of awareness in engineering - but not impossible.
But the given requisite is very unlikely to appear to those kind of people --who simply like to demand explanations. Which, due to psychology it may be they are not listening and, importantly..attempting to understand the given explanation or invoking their own intelligence capacities when reading the explanation. The brain/body interpreting.. and the given data envelope...can each be all over the map, so it is a stroke of luck, almost, if they meet at all.
There is also money on the table, as this fuse scenario and overall market of audio...involves how people hear and what they desire to hear, or like to hear when listening to audio signals.
Depending on the given company, some of that information is shared, some of it is held back as internal lore.
And so on.