That's a bit of a blanket statement. Yes some pop/rock is 'heavily processed' (whatever that means) – but so is some classical. You don't think modern classical production avails itself of all the capabitities of modern digital recording techniques? And if we are specifically talking loudspeakers used in studios I don't see how the needs of classical production differs (or should differ) from any other kind of music ...
It is true that classical music is now almost always recorded using spot microphones and multiple channels and mixed down later.
The big difference is that compression is neither necessary (digital recorders have enough dynamic range) nor done for effect (louder isn't heard as better).
Perhaps live recordings have fewer microphones and less processing, I don't know. Personally I find it regretable that the old ways used by BBC and ORTF for broadcasts and the Decca "tree" and Mercury triple microphone array are not used any more. They picked up more ambient noise but, for me, produced more natural recordings.
A few years ago somebody on another forum was helping out on a recording of Handel's Messiah and they recorded a stereo recording using an old fashioned stereo pair as well as the multi-track mix down. He, with permission, uploaded samples of the direct 2-microphone recording (where the main balance adjustment is microphone position) and the mix of all the spot and environmental microphones.
On my hifi the simply recorded was more realistic, and I preferred it, the only down side was slightly more ambient noise, only noticeable in quiet bits.
I hoped they would issue both recordings but only the mix down of the multi-channel recordings made it for sale.
It is a very good recording with excellent sound quality but I still regret not being able to buy the unadulterated one which was my preference.
Spot microphones are very good at avoiding picking up background noise but the frequency balance 5" from an instrument is nothing like what you get 20+' away so needs manipulating to sound natural and, of course, once all these microphones have been manipulated and mixed together any phase information is completely lost from the stereo.