Advances in technology
Are advances in guitar technology useful except for anything except improving the profits of the vendors? Let's look at some of what's come onto the market in the past forty or fifty years, how it was marketed to musicians, and how musicians benefitted in the long run.
Amplifiers have gone through a lot of changes. Fender tweed amps were replaced by blackface and then silverface amps. Each era of amp introduced a cleaner sound with more volume. Why? Because performers needed more volume to cover the larger venues they faced as electric guitar music became more popular. Remember, this is still in the days when all of a band's sound - except the vocals - came from the backline.
It wasn't just volume that changed. As their amps got louder, Fender changed the voicing to reduce midrange response. Rock 'n roll with its distorted guitars was not yet mainstream music. Fender wanted to make it more difficult to drive their amps into distortion. Over the course of about a decade of amp designs, they settled upon a fairly aggressive midrange scoop centered right around the fundamental frequency range of the instrument. Knock out most of the instrument's fundamental, and what's left is the harmonics. Those upper-range frequencies cut right through the cymbal wash for rhythm parts, and carried well over the other instruments for the solos of the era.
Speakers changed, too. Alnico magnet speakers with their lower efficiency and earlier breakup gave way to ceramic magnet speakers. Nothing changes in isolation. Ceramic magnet speakers are substantially heavier than their alnico counterparts. In fact, marketing literature of the day used magnet weight as a selling point. But the pine cabinets of the earlier era were already causing some problems for travelling musicians. And more weight in a flimsy cabinet was only going to aggravate the problem. So plywood cabinets made their entrance.
Plywood cabinets certainly improved the durability of the amps. So did the replacement of tweed covering with tolex. But the more rugged cabinets also eliminated the resonances that gave the earlier amps part of their sonic character - hit a loud chord, and the cabinet would literally ring at certain frequencies.
Still with me? OK, there's another ripple-effect change. The cabinets no longer resonat, so the new amplifiers sound a bit "dry"... Enter built-in reverb.
Meanwhile... Remember rock 'n roll? Yup, it's gaining a foothold. Distortion is cool, and a few manufacturers develop fuzzboxes to get distortion out of the newer, louder, cleaner amps. Some players still crank everything up to get their distortion, but sheer volume is not always an option for distortion. Why not use a smaller amp? Because the smaller amps are not as desirable from a marketing standpoint - power sells. And lots of players still use clean sounds and need the headroom of the larger amps.
OK, so power sells. Amps are getting bigger. And heavier - plywood cabs, ceramic magnets, more speakers... This sets the stage for the next "improvement": solid state amps. Solid state designs promised - and for the most part, delivered - more power with less weight. Solid-state amps also eliminated the supposed enemy that caused the failure of tube amps: heat. Tubes generated heat when idling, and they "burned out", just like light bulbs. Solid state amps idled cold, and were therefore supposed to be more reliable. Mmmmm, yeah. But they were fragile in other ways. Get a short in the speaker plug of an early solid state amp, and it's dead in less time than the blink of an eye. There were other problems, too. Solid state amps are notorious for their background hiss, and for sounding really awful when pushed into distortion. Still, they were the future for a few brief years.
Now we're into the 1970s. Hendrix has paved the way for distorted guitar sounds, leading other players to seek their own signature sound. This opened the door for "hot-rodded" amps from a number of builders. These amps didn't need a pedal for distortion. No pedal for distortion, but you need a footswitch to get back to your clean sound. This is a noteable difference from the old-school approach, in which the player used picking-hand touch and the guitar's volume control to change between distorted and clean sounds.
The 1980s saw a move toward big racks full of analog and digital processing. Specialists set up businesses to integrate all the components of a big rack rig. This is probably the time when people started bringing in the audiophile perspective, with interest in the quality of the signal path. Granted, the signal path was long and torturous in these rigs, but fancy cables and custom-built effects were not so much a solution as a panacea.
A few things happened in the 1990s. Guitar rock returned to the popular airwaves with Tool, Alice in Chains, Perl Jam, Stone Temple Pilots and others creating a new, aggressive sound. A few years later, other bands hit the limelight with detuned and seven-string guitars. Eventually, the guitar sound was reduced to either a buzzsaw grind or a percussive thud. Amp designs accomodated this new aggressive sound. At the same time, a lot of baby boomers were reaping the benefits of technology stock options and had cash to burn. These guys (and most of them are), with their access to the internet as a medium to exchange information with like-minded players, understood enough about technology to grasp the purported benefits of low-capacitance cables, true bypass, NOS tubes and parts, hand-wound pickups and transformers, etc., creating a market for boutique amplifiers, effects and guitars. At the same time, digital modeling amps were designed to cover the tonal spectrum from vintage through modern. That's great for the amp manufacturer, who only has to build one model to satisfy everyone's needs. They satisfied a lot of players, especially those who needed the versatility.
Now the way I see it, there's a lot more data than there is useful information. The 'net has seen to that. This has created some interesting mismatches: bedroom players using tube amps at conversational levels, and vintage afficionados trying to find their tone in gear that has been refined far beyond its original design. But that's the price of progress...