Why Dumbledore kept mum until the very end of the "Deathly Hallows"?

Question

Dumbledore always let Harry try his strengths. But in desperate times as in Deathly Hallows, is it right for him to have kept mum? During their exile, Harry asks Phineas Nigellus if he could bring him Dumbledore. But surely Dumbledore, though dead by then, but being an extremely powerful wizard, could have devised numerous ways to communicate with Harry!

At the very end of Deathly Hallows, after Voldemort is dead, we see that Harry is able to communicate to Dumbledore via his portrait regarding the resurrection stone. If he was able to do it at that time, why not much much earlier, when he was treading his path with skepticism, in thirst for the numerous truths like the Sword of Gryffindor, Dumbledore's extraordinary life, the Deathly Hallows, etc.? Wouldn't it have made everything simpler and perhaps could have brought about the death of Lord Voldemort way earlier?

Answer 1

• First of all, none of the things your proposal lists would have helped Harry:

  "If he was able to do it at that time, why not much much earlier, when he was treading his path with skepticism, in thirst for the numerous truths like the Sword of Gryffindor, Dumbledore's extraordinary life, the Deathly Hallows, etc.?"

  1. Sword of Gryffindor - as per Dumbledore, it couldn't have been simply given to Harry:

     “Good. Very good!” cried the portrait of Dumbledore behind the headmaster’s chair. “Now, Severus, the sword! Do not forget that it must be taken under conditions of need and valor ("DH", "Prince's Tale")

  2. Dumbledore's extraordinary life

     In short, none of the details of his life were relevant to helping Harry (we'll discuss the Hallows later). If you have specific points/examples, please note them explicitly.

  3. Wouldn't it have made everything simpler and perhaps could have brought about the death of Lord Voldemort way earlier?

     Not that I can tell. Harry still needed to find all the Horcruxes and destroy them (note that only one of them was destroyed by the Sword; and none of their locations was known to Dumbledore to be told to Harry). Harry still needed to perform his sacrifice in order to have Voldemort kill the last soul piece residing in Harry

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• The only thing he could have told Harry about earlier - the Hallows, he didn't want to (and admitted later that it was a mistake for him to do so).

  • Dumbledore was (as he admitted, mistakengly) worried that Harry would be too distracted by the Hallows, like he was, to deal with Horcruxes:

    “Can you forgive me?” he said. “Can you forgive me for not trusting you? For not telling you? Harry, I only feared that you would fail as I had failed. I only dreaded that you would make my mistakes. I crave your pardon, Harry. I have known, for some time now, that you are the better man.”
    “What are you talking about?” asked Harry, startled by Dumbledore’s tone, by the sudden tears in his eyes.
    “The Hallows, the Hallows,” murmured Dumbledore. “A desperate man’s dream!”
    “But they’re real!”
    “Real, and dangerous, and a lure for fools,” said Dumbledore. “And I was such a fool. But you know, don’t you? I have no secrets from you anymore. You know.”
    “What do I know?”
    “Master of death, Harry, master of Death! Was I better, ultimately, than Voldemort?” ("DH", "King's Cross")

  • Hallows weren't integral to Harry defeating Voldemort as far as making Harry "The Master of Death" (and the following quote even stronger reinforces the last bullet point as well):

    “Why did you have to make it so difficult?”
    Dumbledore’s smile was tremulous.
    “I am afraid I counted on Miss Granger to slow you up, Harry. I was afraid that your hot head might dominate your good heart. I was scared that, if presented outright with the facts about those tempting objects, you might seize the Hallows as I did, at the wrong time, for the wrong reasons. If you laid hands on them, I wanted you to possess them safely. You are the true master of death, because the true master does not seek to run away from Death. He accepts that he must die, and understands that there are far, far worse things in the living world than dying.” ("DH", "King's Cross")

Answer 2

Dumbledore's portrait even says that he did not tell Harry about the Hallows because it was a "side quest". Harry's singular goal was to destroy the horcruxes. Dumbledore telling harry outright about the deathly hollows might have changed Harry's priorities (or so Dumbledore thought). He gave them the hint, and let them work it out, but at the end of the day it didn't really mater. Especially confirmed knowledge the ring was the resurrection stone Harry may have spent all of his time talking to Sirius or others who had already died instead of continuing his mission.