DavidSauls said:(2) Par gives us a measure of portability between courses. If I tell you I shot 62 yesterday, what does that mean? Good? Bad? But if I tell you I shot 5 under par, it gives you an idea; better if par were more consistently and accurately set, but still, a better idea than the raw score.
This is the best reason I see for using par. In this area if I shoot a 62 at Mt Airy that would be something to tell people about, on the other hand a 62 at Winton Woods would be something I would never want anyone to know about.