Nobody wants exclusion of any technology, thats the entire point. Especially when its been shown repeatedly that once you implement one of the 3 (fsr, dlss, xess) techs, the other 2 take almost no effort to add in as well. So little effort that modders have managed to shove them in to games that exclude them for whatever reason, sometimes achieving it in a matter of hours.

All that said... Dlss is definitely better quality than fsr. "Some people might tell" is an understatement.

Your 3080 cant run frame generation because it wouldn't improve your framerate with that gpu architecture. Just like software dlss wont improve framerate on a 1080.

Nvidia isnt some boogeyman holding back these techs because they just want to force people to buy new cards. They are definitely making tech that only works on the newest cards to try and get more sales, dont get me wrong, but its not arbitrary.