The semiempirical rule, “Rule 07” specified in 2007 for P-on-n HgCdTe photodiodes has become widely popular within infrared community as a reference for other technologies, notably for III-V barrier photodetectors and type-II superlattice photodiodes. However, in the last decade in several papers it has been shown that the measured dark current density of HgCdTe photodiodes is considerably lower than predicted by benchmark Rule 07. Our theoretical estimates carried out in this paper support experimental data. Graphene and other 2D materials, due to their extraordinary and unusual electronic and optical properties, are promising candidates for high-operating temperature infrared photodetectors. In the paper their room-temperature performance is compared with that estimated for depleted P i-N HgCdTe photodiodes. Two important conclusions result from our considerations: the first one, the performance of 2D materials is lower in comparison with traditional detectors existing on global market (InGaAs, HgCdTe and type- II superlattices), and the second one, the presented estimates provide further encouragement for achieving low-cost and high performance HgCdTe focal plane arrays operating in high-operating temperature conditions.