The actual real world curve is a result of the combination of exposure and developing, and changing these curves is something accomplished photographers do all the time. You are changing the curve of your film when you under expose it. The charts are very good ways to compare the exposure performance of one emulsion to another. A place to start. Pick one emulsion and learn how it performs under many combinations of exposure and developing. Even if you aren't developing your own film yet you can tell them to pull it or push it one or more stops. Once that is mastered you will be amazed how much you can do with just that one film.