KOF has been better than SF for at least the last 2 generations. I have no idea why people play SF4, SF5 when the KOF games exist. Franchise loyalty is strong.
I would also say that KOFXIII single-handedly ended SFxT's life. Nobody was going to play SFxTimeout when hype KOFXIII just released to consoles.
Btw I love SFxT v2013.
Why people play other games because KOF exists?
Because KOF isn't for everyone, it's simple as that. It's the same dumbass rhetoric that people spewed when Skullgirls came out. A FG by FGC members, for FGC Members, it was gonna kill everything else and be the best FG on the planet bar none and save FGs. There was just one problem. NOT EVERYONE LIKES MARVEL STYLED GAMES.
It's not just a matter of brand loyalty. Even if you didn't like SF4 and SF5, that doesn't automatically mean "Oh, well then KOFXIV is for me". KOF is not a replacement to SF and vice versa. They are two VERY different beasts that have different fan bases for a reason, and it's not simply due to advertisement and brand loyalty and anyone who thinks otherwise has their head way too far up their ass.
I honestly hate tier list I don't want to look at them because they somewhat cloud my judgement and want to make excuses to myself when I lose "oh well he's top tier" no, "we will win our way!" -Me talking to myself.