[2019] Why can't I recalibrate the full attribute amount?

I'm finding it rather frustrating when I find a weapon that has a high attribute value that I want to use for calibration, but when I attempt to do so, it caps the value and reduces it by a good 20% - 50%. I would understand if I was transferring a stat from a piece of gear that had 1 attribute over to a piece of gear that has 2 attributes. But I'm transferring an attribute from a piece of gear that has 2 attributes over to gear with 2 attributes. It should just be direct copy/paste of the value with no diminishing returns.

I mean, it's bad enough we can transfer across different colors, but this just seems completely unnecessary. Unless I'm missing something?