Quote Originally Posted by MomomiMomi View Post
It's been like this since FFXI. That's about 17 years. Don't expect any change.

The reasoning they gave back then was that they wanted the players to figure it out as a community. They still do that with a lot of things in the game today ("communicate with your fellow players to learn how to progress"), so it's likely still the same reasoning.
No.
It would be meaningless in FFXI because, like a lot of other RPG, calculations involve enemy stats and enemies have a lot of special characteristics and traits.
Estimation is possible, but the variety of enemies makes it limited (for example the game can tell the player character has around 90% hit rate on most enemies with his current equipment, but it no longer work against an evasive enemy)
Giving accurate number like the OP is suggesting is only possible in shallow games like "modern" MMO.