Stoker's widow won a lawsuit and all of the copies of Nosferatu were destroyed. Well, all but one. Every copy today has that source, that accidental source, as its ancestor.

"Bothering to preserve" is a terribly blunt filter. Luck (good: a crazed archivist; bad: a nitrate fire) is too fickle to select for the best.

It isn't just the films themselves: often, we have no sense of a given actor's career. We know that they had a huge impact at the time, but we have only secondhand evidence of it.