I suspect, among those whom are enthused enough about sharpening itself as a hobby and intellectual pursuit, and with the $$$ to spend freely on such things, maybe the guided systems are attracting more. But among the rest of the world in general, for those who just want to keep their working knives working, I've no doubt some form of freehand sharpening continues to dominate by a colossal margin. And judging by what seems to be more heavily stocked in stores these days, I'm sad to assume many others are using pull-throughs for quick & dirty sharpening and don't know any better, or don't care. Nothing quite so depressing as looking at the vast arrays of pull-through sharpeners in stores these days, with a minimum of decent, simple sharpening stones to choose from.
For myself, I trained my hands and approach for the fundametals using a guided system, with the eventual goal being to wean myself from that and do everything freehand on stones. I've accomplished that goal as of several years ago. I've never regretted it and I'll never look back.
I can see the value in a guided setup as a means to set up optimal geometry for the first time on blades that sorely need it. But once that's set, all the maintenance can more easily and quickly be done freehand, with the good geometry creating bevels that serve very well as guides themselves. That's how I trained my hands while using the guided system, by setting up the new edge with clean & flat bevels using the guide and then doing all of the touch-up sharpening freehand, after the fact. Good foundation geometry naturally lends itself to much simpler freehand maintenance sharpening going forward.