I agree. And while its useful for us to pretend to believe it was based on Russian information, there were probably no Russians involved. If it was true, there might be Russian involvement, but since it was fiction, it was probably entirely written by, as you say, Ohr and Simpson.
Letting Steele sign it and sell it gives it some faux legitimacy, and blaming Russians lends protection on perjury. Both Simpson and Steele have refused to vouch for it.
That doesn’t mean there are no Russians involved at all, though. Fusion was simultaneously on contract to DNC and the Russians. Steele himself was working for Deripaska. And of course the infamous “Russian lawyer” who went to Trump Tower was Fusion.
The dossier’s ‘Russian Connection’ may well be Nellie Ohr herself:
“Nellie Ohr graduated from Harvard University in 1983 with a degree in history and Russian literature, studied in the Soviet Union in 1989, and obtained a Ph.D. front Stanford University in Russian history in 1990. Nellie Ohr was Professor of Russian Studies at Vasser College during 90’s”
https://www.conservapedia.com/Nellie_Ohr