It is suitable for "temporary" ignore some fields in order to make some technical works with some fields during the regular working sync) for example: email delivery over the big amount of clients with temporary changed email field during the active updates of the client table (but we want the email field to remain non-changeable)
At the moment, to stimulate this, we need to build complex combinations of wrap_receiving, additional_data, mapping_overrides, only and etc.
It would be nice to have the new option with both dynamic and static behavior (in order to calculate ingorance list in runtime or in load time)