If i interrupt a external OCD task (lightswitch example) then SO compensates by doing more internal tasks, it just shifts to something that is not external and thereby not stopable by anyone.

This all is allready with meds, without meds a 'normal' life would not be possible.

On a logical level they understand that the world dosent end if the task isnt finished, but to deeper parts of the Brain it still feels real, and the stress created by the fear of it is real, as real as it gets.