It is extremely important to properly track your website traffic and conversion data in order to get the most useful data about your business's website performance. Unfortunately, many businesses don't do this because they either don't know or don't care.

http://conversionxl.com/5-things-youre-measuring-incorrectly-digital-analytics/

The article says that a lot of companies actually depend on the opinions of the managers in charge about whether the marketing is working, instead of basing it on solid data, from say, Google Analytics. Then there are those that consider data measurement to be important but do not have it set up correctly and are not tracking all stages of the conversion funnel.

I'm willing to bet that if data measurement and tracking were properly implemented and analyzed, a lot of employees would be out of a job due to lack of performance.