ps4 is not comparable to 7870but to 7850 which wasnt top amd card even in 2012 while ps5 gpu is comparable to amd top 2019 5700xt, also both ps5 and xsx push the new borders in terms of power consumption and console size, they are almost max what console could look using amd parts in 2020 while in 2013 specs where rather dissapoitment
Its actually closer to a 7870 in performance, the PS4 it is. Which was atleast a mid tier GPU in 2012/2013 (got replaced by a R270??) and no missing important features like RT is today (or even DLSS).
5700XT is close to what a 6700 or a 3060 is in normal rendering, which is the lowest AMD and NV have to offer now.
2013 consoles had the ram advantage and core count advantage aswell (this did play a role in ports etc).
If the 2013 consoles where a dissapointment, then sure the 2020 ones are. The GPU is still the most important factor for gaming, and here they are the lowest tier as compared to 2020 parts, and compared to NV, subpar RT performance and no DLSS equal tech (as of yet, and if it will come, not on-par like RT).
CPU wise its in better standing as the 2013 ones, but still mid-tier of whats available to PC gaming setups. As far as ram quantity goes, this time around consoles sport 16GB total for the entire system, whereas a higher end GPU has that amount or more just for the GPU/VRAM, again no sharing of bandwith either.
A low-end GPU by 2020 nv/amd products, not even counting RT or reconstruction, mid tier CPU with some cutbacks, and a ram size that matches what a single 6800 sports enterily for itself. Not even discussing missing features like IC and other RDNA2 stuff.
Its the SSD thats 'highend', but then were looking at compression aswell. Before compression, were at 7gb/s for high end nvme drives for pc, with DS/RTX IO, were looking at numbers the PS5 wont touch.
'Dissapointment' is something misplaced anyway in a box costing 400 dollars. No matter what, its always going to be a dissapointment if you compare to gaming pc's (costing much more to start with and not hampered by temps, form factor, power consumption, development time etc etc).