Well, first off, the fact-finding expedition was initiated by Republicans, and only later taken over by Clinton. Republicans seem to forget that.
Secondly, it wasn't about finding "dirt", it was looking to Russia to find facts. That the facts being found were troubling enough to be of interest to the FBI is not down to Clinton.
Thirdly, Clinton didn't hire Steele, know he had been hired, or know what he was doing.
Fourthly, Steele was hired, perfectly legally, to find these facts, in exchange for money. The Trump campaign offered to change policy re Russia, which is a crime.
Fifthly, Steele's information was not stolen, unlike the "dirt" on Clinton.
Sixthly, neither Steele nor his sources were working as agents of the Kremlin, while the Trump campaign's sources were.
Seventhly, Steele went to the FBI himself, and the key figures at Fusion GPS have testified to having hired Steele and having been hired by Clinton. Trump's team didn't inform the FBI (despite having had a briefing from the FBI saying that Russia was a threat and that they were obliged to provide any information they had), and have lied about the whole process many times, including under oath.
That's probably not an exhaustive list, but it'l do for starters.