Interesting discovery but its always been the case to be able to do this - the script debugger reveals the player naming convention.
The LocalPlayer was introduced to make things easy, the problem with this guys method is that there may still be mismatch and serious errors if he executes a script affecting say 'player0' but that player doesnt exist. Also, with that convention, its not always possible to detect who and where a specific player number is.
This is also why LocalPlayer was implemented - if you have a 4 player map but a generic script that does something to player numbers 4 - 7 then your more likely to get an error
Theres a bug somewhere in the LocalPlayer code, if they fix that then online scripted maps will work properly without mismatches (and for that matter so will mods that use custom scb file in place of the Generals ones).