This bad take was already debunked
five years ago.
The fact is that the film was only in the public domain from 1974-1993, and since then has only been aired 2-3 times per year -- and yet the film continues to get high ratings every year.
Also, there have been literally thousands of movies that were in the public domain. If that's all it took to manufacture a perennial classic, don't you think that the mass media companies would have generated few more of them by now?
Also, calling it a box office bomb is like chanting "Scoreboard!" in the first quarter. Do you even know the name of the top-grossing movie of 1947? Exactly. Nobody does. Because it was sanitized pablum trite, designed to appeal to a 1940s audience. It had no staying power. (For the record, the top grossing film of 1947 was
"Welcome Stranger", a vehicle for a bunch of awful Bing Crosby songs. It has a 67% rating on Rotten Tomatoes. You know how many times "Welcome Stranger" has been aired in 2021? Zero.)
IAWL was ahead of its time. The people of 1947 didn't know what they had.