“If we can’t talk about the real, actual emails that came about by way of Wikileaks and (alleged) Russian hacking, then why is the garbage Steele Dossier somehow an acceptable foot-in-the-door to investigate Trump?”
Good question: The answer is that Wikileaks were given the Clinton emails by a disgruntled DNC member angry at Bernie Sanders being cheated out of the Democratic Nomination. Julian Assange says the Russians had no involvement. But the emails prove that Hillary Clinton is unfit for public office and probably should be in jail, so they have to be wrong, inadmissible in court, or denied to be real, because accepting them destroys the Hillary Clinton supporters model of reality, and shatters their echo chamber for all time. They simply cannot believe this, without bringing their entire world-view into question.
For the same reason the unverified gossip in the Steel dossier has to be true because Steele was guided by the purest motives: He hated Donald Trump and would do anything to keep him out of the White House, and ……$160,000!
The emails, however relayed to Wikileaks were real, written by Crooked Hillary herself. The Steele dossier is made up, falsified by a self-admitted Trump-hater.