Total fiction ~ no attempt at realistic representation of locale ~ phony phony phony.
Avatar lost it when...... well, when it used a trick out of Gulliver's Travels ~ the floating landmasses. I expect something more up to date than that, or, if used, to have some plausible explanation.
These films are all flawed, some moreso than others.
I’d say Avatar lost it when it became apparent you were watching “Pocahantas In Space”.
You were right, close encounter is not my top 25 favorite.
I only used it because of the same e.t. theme which came out at the same time as an example, and which was not a ‘blockbuster’.
Never saw avatar, so I wouldn’t know what your meant.