Because most games are made in UE4/5, which has not bad, not great TAA in case of UE4 and better TSR in case of UE5 but both still do not compare to DLSS. You forget that you also have DLAA mode which basically is native, and in FSR3 you have Native mode literally.
Studios won't waste time developing new TAA techniques and fine tuning it when they have DLSS, FSR and XESS solutions that are more or less plug and play. And even when they do like in case of Insomniac it still looks worse.
Matter of fact is DLSS, XESS and even FSR are state of the art temporal upscaling/temporal AA solutions. You can run them at native if you like.
If you don't like temporal solutions as a whole then I don't know. Turn it off where you can and enjoy Native, no AA image.
If not TAA then what is the better solution? MSAA? FXAA?