Once you contract a firm, the work they perform should then be vetted. I do not know the history of Fusion GPS, but I do know that PerkinsCole did not sufficiently vet the Steele Dossier. The fact the Republicans first brought in Fusion GPS is irrelevant.
How would they vett it, exactly? Because it's odd that your argument seems to be "the law firm should have done the job that this other firm did when they hired them." In fact the steele dossier is not completely false but has several verified facts in it. The blackmail bit wasn't true but other parts, like Russia helping Trump via social media and Trump attempting to get a Trump Tower in Moscow, was very accurate. So based on that, their history of successful investigation, and the investigator being the former head of Russian intelligence at MI6... There is sufficient evidence to conclude that they were vetted as well as can be expected.
Do you have any links to any formal corporation that produced material about PizzaGate?
Produced, no. Pushed, yes. Infowars heavily pushed it. But fair enough, pizza gate was born from reddit posts.
Has there been any formal pronouncement from any reputable authority concerning any allegations made by a formal corporation concerning PizzaGate?
Fair enough.
Only some Trump officials helped push it and other conspiracy theories. And Trump's main push was about Clinton's emails. No official corporation made opposition reasearch, public.
Even so, you're agreeing that this law firm had no knowledge that part of the Dossier was false. Your entire argument is that they should have vetted the source better but the source was a source of authority and experience so the vetting was done and no evidence has emerged that this was known to be false. Even Trump's own administration agrees that the FBI had good reason, upon reading the Dossier, to investigate its contents. So I'd think that if Trump's team agrees that the Dossier was valid enough to warrant investigation, no law firm was going to do better.
It should also be noted that Trump did not take any action against the law firm until now. He did not make this EO back in 2017 or 2018. Why? If this is so bad, why didn't he?
Because its not about integrity, it's about vengeance. And he doesn't have to worry about reelection.