"Amp in the room" is a myth or a chimera, because, while people talk about their concept of "amp in the room", it doesn't really exist as a concrete, consistent and repeatable thing because it's that person's idea of what their amp sounded like at that place and time. It's not something that can be written into an algorithm and reproduced to everyone's satisfaction.
Modelers can only accurately recreate the sound of the amplifier; That is their litmus test, that the comparison of the output of a real amp is matched by the output of the modeler's amp. Once the sound hits the cabinet in a preset it's altered by the sound of that particular modeled cabinet in that particular room where the IR capture occurred of that speaker, not any other room and not any other cabinet or speaker or microphone. The modeled cab, speaker, microphone and ambient sound in that room will not match any other room or placement of a real cabinet in another room, so getting the modeler to recreate "amp in the room" is not going to happen except by happy accident. Instead, what will happen is the modeler will recreate the sound of a well-tweaked amp into a cabinet with great speakers mic'd by an engineer who was trying to capture the very best sound at several sample points and using different microphones in a studio environment. And, they use near-field captures to try to remove room acoustics as much as possible, rather than far-field captures. The tech notes go over that somewhere or other too. That's the goal of a modeler.
If someone wants to sound like their particular rig's unmiked sound, then they have to take parts of the modeling chain out and substitute the real-world analogs, as Cliff said in the quote above. And, if they're going to be true to their ideal, they'll have to adjust it every time they move the cabinet to a different room because the room will change their perception of the sound of the cabinet.
Cliff's
tech notes are great reading because they explain how an engineer looks at, and works through, modeling guitar amps. He, and Fractal, are after consistent output, which is the antithesis of matching one person's idea of their perfect amp sound in a particular room.