The question asked

It takes Parzival most of the poem to get back. In between he loses his reputation, is publicly cursed at Arthur's court by a messenger of the Grail, refuses for years to serve a God he believes has abandoned him, and eventually finds his way to a hermit, Trevrizent, who turns out to be his uncle and tells him what the Grail is, what Anfortas did, and what Parzival himself failed to do.

Anfortas, he learns, was wounded because he served a love the Grail had not appointed for him — the keeper of the holy thing brought down by ordinary desire. The wound cannot kill him, because the Grail sustains him, and cannot heal, because nothing in the world will close it. The household has spent years watching him suffer and waiting for someone to come and ask.

When Parzival finally returns to Munsalvaesche, the whole apparatus of the tradition — purity, penance, relics, virgin knights — is simply not used. He goes to his uncle and asks him what ails him.

Anfortas is healed at once, and so beautiful in his recovery that Wolfram says no one was ever fairer.

It is worth putting this beside what the French were writing at the same moment. In the Queste del Saint Graal the quest is an examination: no one ought to enter upon such a lofty service before being cleansed and purged of all villainy and mortal sins, and most of the Round Table fails it, and the man who succeeds is a virgin who never needed to learn anything.

Wolfram's Grail is reached by a man who failed once, lost his faith, and came back. What qualifies him is not that he is clean. It is that he finally noticed somebody was in pain.