It's not that simple. Yes, there are accent mikes spread throughout the stage when "studio" type recordings are made. But often times, those accent mikes aren't even cracked open. And when then they are brought up, the percentage of volume that they're adding of any particular instrument - or group of instruments - is usually rather small. That's not to say that microphones in front of an orchestra hear music exactly the way humans do. In some respects, they hear better - more sensitive. But recording engineers are well aware that humans can detect pretty minute differences in regards to balances. I would say that if anything, engineers are often times too conservative - not willing enough to highlight certain effects; or bring up instruments that are sounding deficient in some way.
I'm not saying that the author of this article is outright wrong. What I'm trying to convey, is that it's a more complicated issue than just saying that the solution is to use first versions for recording purposes. First off, why would the author of that article assume that dynamics were always softer, and sound effects kept down more, in all of Mahler's first versions? As I tried to illustrate, Mahler actually reduced percussion and brass in his revised versions of M5/1 (just the percussion in this instance) and M6/4. Mahler often times altered his balances from performance to performance; hall to hall; orchestra to orchestra. He never stopped adjusting his scores in these matters pertaining to balances and dynamics.