Bankers add value? Or just a sounding board and there for legal liability?

Having worked in banking, I have gotten a little jaded about M&A advisory. There is so much analysis that effectively gets thrown away as an M&A analyst because CFOs and their teams don't give a s***. There is also an inevitable firewall between an advisor and its client. The client knows more about their own business and will likely have management with prior IBD expertise, enough to structure and negotiate transactions. I have started to believe that M&A advisors are just there for legal liability reasons and to "double-check" the strategic rationale of their clients. They never drive the analysis, clients do.

I want to hear real stories of when an MD, with the analytical support of his deal team, made a real difference for a company's strategic choices. Post 'em here.