In product and service businesses that are highly commoditized, it should be easy to spot a good deal. Reality is always more complicated than theory.
If you are making a straight product purchase, I would agree this process is easier. If feature sets and quality are relatively comparable, then price leads the discussion.
But what do you when other factors should be considered beyond price? What about product support or expertise? These factors come into play when dealing with situations containing many variables. CRM integration, choosing to change ERP systems or signing on with a new IT service company are all examples of decisions where price should not be the only factor.