The origins of the "identifying" of the whistle-blower come not from any actual fact or confirmation, but from speculation from a right-wing agenda site that bases the speculation upon similar characteristics matching between this person and the description of the whistle-blower.
The obvious problem with the identification is that it has not been factually confirmed by anyone, and circulating speculative gossip because others are doing it is not actual news reporting.
The most obvious analog to why a news entity would not choose to do so would be Richard Jewel, who was originally and accurately hailed as a hero when he discovered pipe bombs in a backpack in a public area during the 1996 Atlanta Olympics and helped clear the area, reducing the amount of killed and wounded when the bomb detonated.
The FBI, still not knowing the identity of the bomber, looked closely at Jewell, himself, because he fit a possible profile of a lone bomber and someone who might look to insert himself into the situations to manufacture the "hero" situation. They talked out of school and because Jewell's life and appearance fit certain stereotypes, this out of school gossip was widely disseminated until there was a public narrative and assumption that it was based on fact.
Early news reports lauded Jewell as a hero for helping to evacuate the area after he spotted the suspicious package. Three days later, The Atlanta Journal-Constitution revealed that the FBI was treating him as a possible suspect, based largely on a "lone bomber" criminal profile. For the next several weeks, the news media focused aggressively on him as the presumed culprit, labeling him with the ambiguous term "person of interest", sifting through his life to match a leaked "lone bomber" profile that the FBI had used. The media, to varying degrees, portrayed Jewell as a failed law enforcement officer who may have planted the bomb so he could "find" it and be a hero.
A Justice Department investigation of the FBI's conduct found the FBI had tried to manipulate Jewell into waiving his constitutional rights by telling him he was taking part in a training film about bomb detection, although the report concluded "no intentional violation of Mr. Jewell's civil rights and no criminal misconduct" had taken place.
In a reference to the Unabomber, Jay Leno called him the "Una-doofus". Other references include "Una-Bubba", and (of his mother) "Una-Mama". Jewell was never officially charged, but the FBI thoroughly and publicly searched his home twice, questioned his associates, investigated his background, and maintained 24-hour surveillance of him. The pressure only began to ease after Jewell's attorneys hired an ex-FBI agent to administer a polygraph, which Jewell passed.
In October 1996, the investigating US Attorney, Kent Alexander, in an extremely unusual act, sent Jewell a letter formally clearing him, stating "based on the evidence developed to date ... Richard Jewell is not considered a target of the federal criminal investigation into the bombing on July 27, 1996, at Centennial Olympic Park in Atlanta".
Wikipedia: Richard Jewell
In addition to the cautionary tale learned through actual mistakes in the past, there is also the caution in the news media of not wanting to be willing dupes in attempts by parties with an interest in the investigation to distract from the central issues.
In reality, the whistle-blower's identity does not matter. Who the person is, and what their motivations are or were are not relevant. The facts of the complaint are what matters. An independent IG found the issues raised to be credible and urgent, which makes the whistle-blower's opinions or motivations to be irrelevant. The first line of phony defense was that the whistle-blower was reporting "second-hand" or "hearsay" information. That, of course, is also irrelevant, but the same people who claim it was very important are now claiming that it's important to hear from this "hearsay" witness after all of that person's claims have already been corroborated by either the Trump administration, or by first-hand participants. The whistle-blower has nothing to add beyond what was in their report, and if anyone has questions about it, those answers can be found in corroborating and, often, more direct testimony from others. There is literally no reason for that person to testify, other than for prurient gossip curiosity.