After turning the feature on, I have Collections based on 2 movies where the second part is coming in theaters within the next two years.
Just auto creating collections when 2 or more movies are in library would be a nice cleanup for the collection view.
I believe this is already in existance:
Settings -> Server -> Agents -> Movies -> The Movie Database -> In the list click the gear next to The Movie Database -> check on Use collection info from The Movie Database
This pulls in the collections for me, you will likely need to rescan your library.
Awesome, did not see it until now 
There is a reason for it not being active by default:
TMDB collections suck. If you leave that active, you’ll see some wacky collections for sure!
Yes, I know what you mean. Now I have a Avatar Collection until the second movie arrives.
Perhaps a feature request would be to just to add a collection if a minimum of 2 movies are in the library.
Early 2021 clean-up: implemented
