I've found those calculators to be a little conservative. They are going with the physics and not necessarily the user experience.
If you are consuming content only then you just see a smaller screen. If you are trying to read 12 type font, that is another matter.
I can certainly read closed captions on small displays at a great distance, my vision is a little worse than 20/20 these days. Generally a quite large font with high contrast. I can read webpages on a 27" screen at about 12-16ft just by zooming to about 150-200%, depending on the site.
By those calculators, I would need an 85" screen. Which, granted, would fill my visual field a lot better.
Actually planning on replacing my old 27" with a 32" or 37" here shortly. Pretty sure I bought that thing in 2010.