In the case of Slackware, I'm going to guess that it's more to do with Patrick's idea of "if it ain't broke, don't replace it". This is why Slackware still come

In the case of Slackware, I'm going to guess that it's more to do with Patrick's idea of "if it ain't broke, don't replace it". This is why Slackware still comes with Lilo by default: it works, so they never switched to Grub (though Grub can be used and is actually also an available package on the installation DVD: the choice is always yours).