I think Carter says it best,when you use jigs & pull thru's etc.you are pushing the respon. to the jig instead of your own skill.A steady spine is important when freehanding,but you can tailor your edges to diff. knives & the jobs they are meant to do.
I know that with wood tools a jig can be helpful,but even these can be freehanded wt. slipstones.JMO think that the best way to sharpen kitchen knives is to learn freehand skills on a whetstone.