That means the lack of huge software like Gnome
Been using Gentoo since Jan 2009 and one of the reasons I moved to it and never looked back was because it let me tailor "huge software" like KDE to my needs, with the aid of USE flags and sets. That's what an actual customizable distro let you to do. If you want to use "smaller software" like, say, Openbox, it won't get in your way either.
So that point of "centered around smaller software" strucks as weird to me - it goes against the "customizability" point and, ironically, the very Linux kernel is "huge software"...