I keep Kubuntu on the Desktop and Slackware on the laptop.
Ubuntu gives me access to a whole lot of software for whatever I need. I use use it for video editing and bit torrent.
For me, Slackware is all business. I use it for WORK, mostly writing and editing text and graphics. Somehow, the uncluttered, straightforward architecture seems to lend itself to getting things done. I feel that I'm a lot more productive with Slackware. For someone else, it may be different.
But it's specialized, and limited. You're just being ignorant when you imply the packages aren't current, but you don't get the easy automatic access to software choices you'll get with a Debian or buntu based distro, but it's a great no-nonsense tool for basic work.
It's also fun to tinker with Slackware. It's been the basis of some of the most interesting and original second-generation distros, beginning with Slax and Porteus, through Vector Linux and zenwalk. I was actually able to release my own homemade live cd based on Slax 6.1.2. I've been maintaining and refining it since 2010.