It’s important to remember that Steele’s dossier is a collection of raw intelligence. That means the information has purposefully not been vetted, synthesized or verified - only reported. It’s basically a collection of notes that have been transcribed from their sources - much like a reporter’s notes when doing a story. They are data points to be investigated further and not to be confused with analysis or conclusions.
It means all the information within can be either true or false depending on who provided it and under what circumstances. It still requires a tremendous amount of work to validate and corroborate the allegations which is what Mueller’s team is essentially doing now, although they are using different sources than the dossier. This is what good investigators do. They don’t rely on a single source of information to build a case.
What we’ve seen however is that most of the broader facts that Steele reported are generally correct and shows a pattern of activity supporting close cooperation between Trump campaign and Russian operatives. So far the parts that could be verified have turned out to be accurate. But that doesn’t mean other parts that have yet to be verified are false. Even if elements like the pee tape ultimately turns out to not to be true it doesn’t discredit the other parts - although that’s exactly what the Trump team is trying to do.
