Unless the actual source file is 120fps, you are still just duplicating or making artificial "mixed frames". The only way that 120Hz will make a real difference is if the video you are watching was filmed at 120fps and the device playing back the video to the TV also supports 120fps.
There is VERY little content that is 120fps, the upcoming Avatar squeals and Andy Serkis adaptation of George Orwell's
Animal Farm. Other than that, a small amount of youtube. Also almost no devices (no PS4, XBox 1, Roku, Fire TV, or Shield, all are 60fps) or satellite/cable providers.
https://www.rtings.com/tv/learn/what-is-the-refresh-rate-60hz-vs-120hz
What good is having tech if you cannot actually get the full benefit from it and wont for many many years? So no, it is not outdated info.