As I've said recently I think Eliezer severely overestimates the readiness of people to let go of perceived patterns.

The indestructible diary was meant by Eliezer to be a red herring for the duration of a couple paragraphs, until the readers were told it was the diary of Roger Bacon, not Tom Riddle. At which point, I suppose readers were supposed to smile at themselves for being deceived.

But of course readers just pattern-matched "indestructible diary" to "super-significant plot-point and Horcrux" and wouldn't let go.