Celestion Vintage 30 A best guitar pickup is basically similar to an energetic mike coil. For decades, dynamic microphones have been wired with the voice coil attached with the primary of the microphone's transformer, and perhaps not referenced to surface (‘floating'). The microphone's case is typically linked to the cable shield, which can be connected to the mike amplifier's ground (see Rane's website for more discussion).
By and large, dynamic microphones are extremely calm devices as a result of the combination of transformer isolation and healthy, hanging indication lines throughout, along with protected, humbucking coils.
Therefore why not instruments? Instruments are once plagued by noise. Humbucking pickups are only an incomplete (though crucial!) solution. Well-known solution is always to float practicing the guitar pickup to a balanced result, being a microphone. A similar idea was published that 2001 patent application like this Celestion Vintage 30?