"So it isn't true yet at the end it is true?"
Exactly it is true if you have a small screen or sit far away from it. It is definitely not true if you have a nice big TV and want cinema feeling (i.e. the viewing angles are big.) Digital cinemas have 4000p or something like that so for a given viewing angle even much higher resolutions like 1080p make sense and can be seen. If it is relevant for your living room I have no idea. But saying people cannot see a difference without pointing out the parameters is simply wrong.
Edit: I just googled and modern cinema systems are so called 4k systems meaning 4096 horizontal resolution or 4096 pixels by 2160 = 2160p.