During high school I was a trumpet player and I always ended up marching next to the drumline during parades and performances. Came home with my ears ringing and couldn't get to sleep half the time. I went to guitar center and got earplugs so I could just be on the field during practices and performances without blowing out my ear drums. My marching band was about 350 people strong at the time.
I had a revelation during my guitar gigging years around 18-19. I was used to having earplugs in and dialing in my amp with them in and found that the high-end attenuation made me set my guitar amp (2204 JCM 800) brighter and more cutting than someone who didn't use earplugs. I dialed in my tone so that it would stay fat, but I could still hear myself during rehearsals.
One gig I left my earplugs at home accidentally and was forced to play the gig without them. I was doing soundcheck and listened to my tone and said to myself "wow, that would cut someone's head off". But, I already had scratches in the faceplate to get "my tone" so I decided to keep them there. I walked out into the venue on a wireless next to the soundboard and listened to my tone while the whole band ran through the chorus of one of our songs and found that the guitar while alone sounded so brash and bright, when the whole band played it sat sooooooo well in the mix. Right undeneath the cymbals, and above the bass and snare without smothering the vocals.
It was a huge eye opener for me. And honestly I can thank the years of earplug use leading up to that moment. So when guitarists talk about losing all the high end due to earplugs, they forget that they can compensate with the mid/treble/presence knob to "get that high end back" and then in the grand mix of your guitar with the rest of the band you wont run into that "Oh we couldn't hear your guitar" thing an audience member will tell you after the show.