I understand how the GBAs work and if you think it cant be done in 4 player split screen and no overhead map...
then it can be done by having the GBA sp box pop-up like it does in single player but instead 4 boxes pop-up in each corner (1 for each player). and each player can turn his/her box off with Z just like in 1 player. Its very possible. Dont say it would be stupid to even think of an idia. I bet if nintendo wanted to they could of made it that way.
Here is a mock-up I did. The individual player screens are only 10% smaller then the one you get in single player.. And If nintendo did not include the Gameboy SP boarder, It would give you an EVEN larger game playing area. And keep in mind that not all 4 windows would be up all the time.. and even if they are they are then they would cover (without the boarders) even less then the window in 1-player since the center would not be covered.
Zelda 4 swords 4 player GCN mock-up(anyway to direct link pics on this forum?)
And why knock split screens in general? Thats what consoles are all about. Go play PC for single screen or Xbox and PS2 which have online play, or only play games like SSBM.