I cannot even keep track of all the films said to be neo-noir, and this includes some like Mars that I have on a hard drive but have not placed on a dvd. Recently I noted here that I had deleted 200-250 gb of such films merely because I didn't want to watch them, and I'm not sure I even saved their names.
And there are more films omitted for one reason or another, including simple inability to know what's neo-noir and what is not. There are lots of films that people proffer on lists. There are obscure films. There are minor films.
For me, there has been benefit in making a big list, but we all face diminishing returns in such a task. That's the basic reason for omissions. It's economic. It doesn't pay after some point.