What in the story changes if Draco never existed?
Ender’s Game battles go another way entirely. More science with Hermione instead of Draco. Hermione doesn’t get framed because the only reason she was is to remove Lucius and protect Harry from his retribution for messing with Draco. Hermione doesn’t die. Trelawney gives no prophecies as Harry is not driven to extremes this year. Final confrontation doesn’t happen at all. Harry helps Quirrell obtain the Stone to save his life, he has no reason to suspect him as nobody has died. I think Azkaban arc stays the same, the rest is completely different.
I wondered about that as well. I think the answer has to be something along the lines of “He could do nothing to conceal it, he new it was a longshot, he lost nothing on the attempt, he had a backup plan he never told Harry about.”
Imagine: Harry tells Dumbledore, Dumbledore confronts Quirrell, he dramatically reveals his identity as David Monroe, as well as a lightning-shaped scar on his chest and a fantastical story about dual fates or prophecy twins or something.
Actually, do we know that McGonagall threatened to painfully kill Harry if he reveals Voldemort’s secrets? It could be a fake memory.