If you want to truly know how 'un-true' that statement is about effects on the guitar you have only to visit Brent Mason's website and see the STUDIO RIG that he brings in with him. Anyone that has spent any time in the studio recording with a studio guitarist (or recording as a studio guitarist) would know that a guitarist brings his tone and his effects in an IF and ONLY if the engineer has a problem with the sound, then he'll add to what's already there OR in extreme cases may try to talk the guitarist out of using a particular effect.

Only guitarists with bad tone or ones that don't know how to properly operate their effects get recorded sans effects and have them added after the fact.