Quite the contrary, at least from where I sit. My take here--and if I had the $$ and time to waste, it would be fun to test it scientifically. but alas... --- is that people seem to massively over estimate their view of "iconic" instruments as "snowflakes". I have 2 Fender strats; build in the USofA. Sure they share timbral similarities, but they sound quite different. My silver sky, as one would expect, fits into the same sonic universe. Which should I assume would fit the platonic ideal of "strat" that some producer thinks he/she has in their heads. Should I assume the Fenders would always be a better fit, for any reasons rooted in sound?? I'm quite skeptical. In a similar vein, I have an Eastman AR372 (think ES175). Sure it does a thing; does it well. However, with a bit of eq, I can make my 594s sound pretty much identical. The Eastman is a good guitar, I really enjoy playing it. However, the sort of bridge that it has is a pain in my ass, and can have it's intonation knocked off if I fart too loudly whilst playing it. I imagine an ES175 suffers from the same, if not greater problems. Given how close I can get I 594 to sound like it (I'd also have to modify my playing, as I approach the arch top differently, but that's not a big deal). Is it better to bring a guitar who's intonation may give fits, just so a producer doesn't blather off some flavor of confirmation bias, lest I bring the more stable and reliable guitar??
While Les said everything I could not figure out how to say in a way better than I could have said, but let me add a little bit about the "strat vs. strat-type" instrument....
Last month I worked on a session for a singer/song-writer that drives me crazy. She's a great singer, her songs are pretty good, but her ego and expectations in her sessions are difficult. Why do I do her sessions? She pays VERY well and often I am challenged as a player - two benefits.
Anyway, she was insistent that I use a strat on this set of songs. She had a VERY clear vision of what she wanted on these tracks. It's another cool/frustrating thing about her. In our discussions of the track, I told her I don't have a strat. She was insistent. I told her I have a PRS version of a strat. She said she wanted a Fender Stratocaster on this batch of tracks.
* For reference, the sound she was after was the 2 position on a strat played clean, with chorus, reverb and dotted eighth delay*
Our conversation got kind of heated. I told her to just hire somebody who plays a Fender Stratocaster - there are hundreds of them (lol). She agreed, but was also kind enough to compliment me by saying, " The guys around here that play strats can't do what you do!"
The compromise? I would show up with my Strat-like PRS, which happens to be a 1990 EG3, I'd let her hear it and we'd go from there. Where would we "go"? Whether or not I got the job. We met up at the studio - ironically the producer was REALLY digging the guitar. His words? "Dude, that's from when PRS made them right!!!" I smiled, but rolled my eyes inside....
Wrapping this anecdote up, Courtnee (the artist) heard the guitar/rig and was MORE than satisfied by what she heard. I got the job, which I wasn't surprised by...I'm pretty much the ONLY guitarist she uses these days. If she ever starts a band it wouldn't surprise me if she'd want me in the band.
But, again, to reassert what Les said....
When a guitarist is playing on somebody else's song, it's not about the guitarist. It's about the song. What the artist hears. It's not always as intense and "picky" as I have said. But, there are times where it is "safer" to bring multiple guitars to a session and let the artist or producer (whoever is really calling the shots) pick the instrument they think sounds best. In the end, what do I care? I don't own any guitars that are uncomfortable to play. I am getting paid to perform a service. I am cool with doing what I need to do in order to keep getting work and making my clients happy.
* Now, if I showed up to a session and was handed a 1940s Kay archtop with OLD flat-wound strings and super-high action, then was told I had to do 13 songs on it, YEAH....there would be a problem and I would "argue" about the merits of my own guitars. But that has NEVER happened. I have been offered instruments that producers own - but I haven't be FORCED to use them, they are just there if I want to give them a try.