let me rephrase this.... Never in my life have I played a gig without a monitor in front of me, or IEM's... Not once, not ever... I'm astounded by how many posts I see like this were people have never played with hearing their guitar thru a monitor...
While it may have already been hinted at, your experiences are not everyone else's experiences. I've probably played more gigs WITHOUT monitoring (save for a shared wedge for the vocalists) than with them. Say what you want about FRFR (and I'm a fan, don't get me wrong), but a guitar sounds different going through a traditional guitar cab vs. a monitoring solution or FRFR. The point that's really different is the addition of the mic to the signal chain (and no one's smart enough to be able to replicate it without... yet). A cranked 5150 on a stage, by itself, through a half-stack of speakers, sounds very different than listening to that same sound through an SM57. Even if that sound is blasted through thousands and thousands of watts of Class D power into a top of the line matrix array of PA speakers... it doesn't sound like a set of Creambacks pushed hard. And, again, the primary difference is not the speaker, but the mic.
The sound of a guitar through monitors, and even more so with IEMs where you're "closed off," just doesn't sound the same. I've gotten used to using modeling and pushing that sound direct to house since, well, as long as Line 6 has been around. But, honestly, one of the best sounds I ever got from Line 6 was pushing an X3 through a Vox AC-15, set as clean as humanly possible. It had the liveness of a real amp, with the benefit of being able to pull up a model of whatever I wanted, and it still sounded great. I've debated doing the same with my Kemper simply for some "liveness," but I haven't tried it.