Of course there are multiple reasons anything happens.
For example Biden also massively benefited from Obama and the rest of the establishment coalescing behind him on Super Tuesday.
And as I already stated he benefited because of proximity to Obama, and name recognition.
But yes, for the fourth time - if the Main Stream media (of which the Democratic Party has a 70+ % Approval Rating) had not given Biden enormous amounts of positive press and thoroughly convinced millions that he was “the most electable“ candidate, he would NOT be the nominee.
Without that he doesn’t win. Full Stop.
You could almost say - it’s the REASON he won.