This is a holdover from FFXI's method of handling stats. It's meant to encourage player collaboration and data sharing. It took players YEARS and YEARS to finally figure out FFXI's algorithm for simple ACCURACY because SE refused to give hints. They've been quiet for a decade and a half on their games' math, so I doubt they will ever add any more transparency to FFXIV. This is the company that included a boss in FFXI that was unbeaten for 2 WHOLE YEARS by ANYONE due to its weird mechanics until SE finally released a video to give people a hint.