Because different engines are developed differently - just because one game developed in a specific engine can do something doesn't automatically mean that another one should just be able to do it in a different engine. PS4/XB1s have both ceased being produced and are at the 10 year mark - its not worth the dev time to go back and optimise parts of the engine to make FoV possible on those consoles, especially with the chance that they may have support dropped for them after final shape.

....touche...