JP, I didn’t want to overwhelm the guy, but I can’t disagree with you too much! I personally use a Focusrite 6i6 to mix guitar and backing tracks as well. The backing tracks come from my laptop, the guitar signal comes from a modeler (Atomic Amplifire 6) and then I monitor with headphones off the front of the Focusrite or with a CLR off the back, both with independent volume knobs which is super convenient. Going from playing along to recording is basically as simple as opening up Reaper.
Keep in mind, there isn’t a “real” guitar amp involved in this chain at all, but with something like a Suhr Reactive Load IR, I could play my tube amps in place of the modeler.
I totally get what you're saying and these days no one really "needs" an amp at all.
In fact, before I bought my new amp, I had no Line Out on the amp I was using, so I would simply plug my guitar into my pedal chain and then the pedals into my Focusrite and then into my DAW and everything worked fine.
My new amp has a Line Out (which for me was a "must have") and one of the major reasons I like it is that if I want to play loud, I can kill the signal to the Focusrite and just have the track play through the monitors (which are in front of me) and the guitar comes through the amp (which is behind me).
This way I can play to the the track and I hear the amp through its speaker with all of its nuance, which of course sounds more "real".
But when things get quiet (like late at night), I can do the same thing by lowering the amp volume (along with the track volume) and balance the guitar and the track through the monitors so that they are both at more of a "bedroom" level , or I can just kill the amp volume altogether and pop on the headphones.
I'm not suggesting than any one way is better than another.
I just like to have a variety of options instead of any kind of "either/or" setup.