No THX sets standards for Audio and Visual equipment in a variety of environments including the home - you can buy THX certified TV's.
They're making a recommendation for setting up a HDTV in a home, if you wanted a tv to stick in the corner while eastenders or the news is playing in the background then - no i wouldn't say its the setup you'd probably find suitable.
However as the OP is looking at one of Samsungs higher end tv sets in sizes around 50" then yes i'd take a leap of faith and guess he wanted something of a high end experience - its not 'just about watching movies' i certainly enjoy that type of viewing experience when watching shows like The grand tour or Game of thrones or house of cards.
As THX point out "2) the biggest complaint among TV buyers is that they wish they had bought a bigger set." ... oh look other posters in the thread find the same thing.
thx also say you should set your bass management crossover point to 80hz, however i think you will find quite a lot with home cinemas don't bother listening to them on that.
when a screen is so big you can only focus on a part of it then you could be missing out on details the director intended you to see around the edges.
put it this way, i wouldn't want a tv any bigger in any of the rooms I have a tv in. the living room only has a 43" screen, bedroom 50" and games room 55".
the one in the living room is on an articulated arm so i can swing it around and pull it closer. it's usually about 6 feet away and perfect for that distance. 55" like i said earlier about 8 feet away and the 50" about 7 feet away.
I'll be buying a projector for the living room at some point but that won't be for day to day use only movies and special occasions.