I never played it but I saw videos of other people playing, and I wasnt the only one who commented "how come the bosses are so slow?"
Maybe they had the game speed set a lot slower.

Im betting on the second, I checked the monster listings of this site for FF IV and all monsters in my game have at least 50% more HP
That's funny, because the FFIV section of the frontsite isn't based on the GBA version. It's based on the version you're playing. How do I know? Because I coded it.

The first time I beat this game was on a ROM of the SNES hard version. After that the Super Nintendo easy version did pale in comparison. Several years went by before the PS version came out, and then eventually the GBA version, and they did seem pretty easy to me too. I don't know if they really were easier, if if I just got better at the game beating the easy SNES version so many times between the hard versions. It could also have been that the hard version was my first play through the game, so I would naturally be better at it anyway.

No matter what the reason, it's easy enough to tell which version someone is talking about without freaking out over it. Nothing about the forum is going to change because you're unhappy about it.