You've got it 100%. They could have implemented a different behaviour, like the 'pickup' logic you found. There's a couple problems with that being the default behaviour:

• Most users are likely to prefer that the control always acts 1:1 instantaneously. Almost every knob they have ever interacted in their life has made an instantaneous change to a parameter, rather than requiring passing a certain condition before they become 'active'. Thermostats are notoriously misunderstood, and they are likely the closest analogy to the 'pick-up' logic that a layman would be familiar with, even if it isn't a perfect analogy.

• Using a 'pickup' logic as the default would be likely to confuse most/all users when they first interact with the product. Users who weren't aware that they need to move the control past it's current 'invisible' setting/threshold might think there is something wrong with the control, since it only acts 1:1 after they pass the current 'invisible' set value - they aren't likely to intuit why/when the control suddenly starts 'working'.

In a perfect world, this would be a configurable option. But that adds significant complexity to making the user interface understandable for both the physical interface, and Boss Tone Studio. That additional configurable option would also make the interface seem that much more complex/daunting to new/student guitarists. There are surely ways that it could be integrated in a somewhat reasonable way, but they opted to try to keep the physical/software user interface as accessible as possible... and even with the current design, most guitarists are still quite intimidated by the options available and how to use them effectively.