IMO Giuliani was trying to discredit Biden's Presidency, similar to how the Steele dossier was used to discredit Trump's Presidency. In both cases, innocent people were caught in the crossfire.
The reason you think the Steele dossier was a joke is the same reason those people stormed the capital and millions of people believe the Trump actually got more votes than Biden. Trump repeated it over and over and over, and so Republican lawmakers and the media repeated it over and over and over. and so you repeated it over and over and over.
In reality, there's far more disinformation
about the Steele Dossier than in it. A lot of it has been confirmed, including the most important point - that the Russians were planning to influence the US election by helping Trump win. Most of what hasn't has confirmed has been determined likely true.