Do not seem as unaccesary high in context of the sheer amount of details in the PS5 Version. The Devs stated for example that they use for Joel and Ellie the Cutscene LOD in Gameplay. Also all other Assets of very high quality. Much higher than on other Games. Naughty Dog are wizards with this. Thats why Joel in TLOU2 was looking better than most if not all other Game Protagonists. If zlib is that much more effiecient the reason they went anyway with oodle must lie in project management. Maybe it was simply not possible to to transfer the Assetsdata to zlib. But again - i rather life in a world where PC Versions of PS5 First Party Titles ask for just a little bit more, than having a PS5 game developed with a comming PC Version in Mind ( with all the problems that might bring , look all the quad cores still in use or GTX 1060s out there). And suprise - the latter pathway would eventually also have the PC Version gimped because also the high class systems then would "suffer" from a port that could have aimed higher. PS5 first with all bells and whistles!! Then try to make the best PC Version possible based on that Version - if certain systems suffer they suffer.
As for Direct Storage - yeah thats a shame i would have loved to see it compare to first party PS5 usage. But the easiest explanation is mostly right. They might just not had the time to implement it. Or Project was started without it being a thing and the later turnaround would have taken to much resources , who knows
Oh - i dont have to be that elaborate - i dont release Youtube tech Videos about the matter. But i can criticaly ask questions . And if theres is bias to call out - iam sitting in the first row.
@ tech use - we simply have more third party comparisions than first party PS5 titles who made it to PC. I wonder for example how Ratchet and Clank would run on PC System. I highly doubt that the Ryzen 3 3600 / RTX 2070 super would be able to mimik PS5 Quality and FPS.