because it's less work. i don't have to strip out what a distro thinks i want. i don't have to worry about major distro releases that might have changes that need manual intervention. if there are updates that need manual intervention, they're small, easy to deal with and usually do not effect me. everything is well documented and standard. packages are installed with default settings/config (to my understanding), so i can easily read upstream documentation and not have to deal with weirdness. getting packages that are obscure is easier. i don't have to worry about upstream having a fix, or supporting something that i need but my distro not having the update in their repo. it's just simpler and easier to manage (for my use case)