Do We Need Attribution?

Marketing needs to be based on actual business results, not vanity metrics. If we spent 200 thousand dollars in marketing month, and we generated five and a half million dollars in pipe line, and we win that pipe line at 30% or 25%. Do we need attribution, or is that just something that people have been told? And so if we think about total marketing spend against total marketing outcomes, then from there, it's marketing job to figure out what are the signals that i'm looking for  to decide which parts of the 200 are the most effective,. Some of those you can use software; some of those you need to use other ways to measure Marketing.