I couldn't defend it as such in a general sense, but the reason I always liked Slackware was minimalism. It never had that as an explicit goal, but it was for a long time a distro great for people who wanted minimal systems, without any 'wizards' to get in the way. It kind of lost it's way trying to comepte with things like Ubuntu though.

Alpine is so much better from a minimalist point of view (a functional minimal desktop install is only 700mb, while on Void, Devuan and Gentoo it's about double that), and that it has security as a priority at the forefront is icing on the cake.