You use ads in B2B to build leads, then you follow up with marketing/sales. Certainly you wont get a conversion with display ads, but on certain providers they can help feed into the start of your funnel.
End of the day, the salesman and his relationships closed it. The marketing consultant made a lot of cash though.
That said, ABM is increasingly popular for businesses where it makes sense. Why waste time and money filling the marketing funnel when you can identify preferred customers and invest in building a relationship with them.