As has been stated, the RCAG may not actually be in the controlled sector and some sector frequencies are present at more than one RCAG site. So knowing both the sector frequency and the associated RCAGs are important for knowing what frequency to monitor and your possibility of hearing the ground site.
I attempting to updated RRDB listings it appears the ZNY no longer lists sector names, only numbers, in their recent documentation. So we may have to rely on the numbers in the future.
Also, with the FAA staffing shortage sector are often combined, at least on certain shifts, to add to the confusion of what frequencies to monitor.
ATC monitoring presents different challenges from conventional monitoring which the RRDB format is designed to support. So the present format of listing ATC data by Center and then by RCAG sites with their associated sector frequencies is the best way to meet the objective of providing frequency info to program your scanner based on geographic location. A fundamental principle of the RRDB is all frequencies are geocoded to facilitate location based scanner programming. So this is tied to the associated base station transmitter site coordinates.