In the context of Pure Cab we are talking about trying to remove the phase type relationship that you get with a mic to make the sound more like an amp in the room.
“As mentioned in the previous chapter, mic'ed guitar cabinets often have an unpleasant, “phasey” sound in the high- end frequencies – something you don’t get if you listen to a guitar cabinet directly, without a microphone. "Pure Cabinet" will gently polish the sound of the virtual (mic'ed) guitar cabinet to bring it closer the sound of the direct guitar cabinet. The fundamental character of the sound will still be maintained.” : From the manual.
Whether it’s a Kemper profile or a mic’ed cabinet on a recording, it’s the same issue. That’s probably why lots of people hate pure cab and say you should never use it. Some commercial profilers “advise” turning it off to avoid screwing up the sound of their carefully captured profiles. (Personally I don’t mind it and leave it on at a low level most of the time but that’s just my personal preference). Many people would argue that pure cabinet doesn’t acheve the amp in the room effect it’s intended to. Others think it does. Therefore, my point was simply that I think it would be better to not introduce it (or something similar) at the profiling stage but simply capture the purest profile and add something like ure cab to tase afterwards.