As long as the personalizations are just a transformation and not a subtraction
This is the crucial point. As long as it's accessible, I can get what I want by search refinement either way (but I would imagine that it would be easier for me to refine in the space in which I am familiar than to refine in the unfamiliar space). Giving me the (easy) option to turn it off is a good idea for search.
This is the crucial point. As long as it's accessible, I can get what I want by search refinement either way (but I would imagine that it would be easier for me to refine in the space in which I am familiar than to refine in the unfamiliar space). Giving me the (easy) option to turn it off is a good idea for search.