Two data points - financial data especially - don't give you a lot of information. And it certainly isn't a basis upon which major decisions should be made. But how frequently do you read in the newspaper or journals that first quarter sales/GDP/housing start are up/down 5% and how great/bad that is for the company/industry/country?
While I am nothing like an expert (that would be Donald J. Wheeler and his very readable Understanding Variation), nearly everything can be described as a process - and it is the behavior of the process which needs to be monitored as a whole. Simplistically, If I know that on average sales grows by 3% with variability of +/- 3%, then I probably shouldn't get too excited when it only grows by 1% or if it grows by 5%. Process behavior charts help look at how the process behaves over time and can help show how the process is expected to behave. And they help illucidate lurking problems in the process, which would not be apparent upon examing the data for the last two quarters.
Please, read Wheeler's book to fully understand the nature of the process before deciding that you need gallows or gifts when reviewing your latest figures.