Future space missions that aim to detect and characterize Earth-like exoplanets will require an instrument that efficiently measures the spectra of these planets, placing strict requirements on detector performance. The upcoming Roman Space Telescope will demonstrate the performance of an electron-multiplying charge-coupled device as part of the coronagraphic instrument (CGI). The recent LUVOIR and HabEx studies baselined pairing such a detector with an integral field spectrograph to take spectra of multiple exoplanets and debris disks simultaneously. We investigate the scientific impact of a noiseless energy-resolving detector (ERD) for the planned Habitable Worlds Observatory’s (HWO) CGI. By assuming higher quantum efficiency, higher optical throughput, and zero noise, we effectively place upper limits on the impact of advancing detector technologies. We find that ERDs would potentially take spectra of hundreds of additional exoplanets “for free” over the course of an HWO survey, greatly increasing its scientific yield.