Except they released the game, in "enhanced" version, on the Switch, which is just old android phone hardware from several years back.
Specifics matter in this case.
My quick review of specs shows the Switch having a 4GB of RAM to work with. Not a lot, but enough that even with the OS, you shouldn't run into too many problems.
The PS3 had 512MB of RAM. But actually, 256MB was dedicated to video, so it only had 256MB for the game itself. Oh, and the OS used a chunk of that. So, the PS3 has less than 256MB of RAM that is usable by the game. And that's where you are running into issues, especially in a game like Skyrim that is heavily reliant on memory for the amount of state the game tries to keep track of.