I think we're overthinking the recurve bit. It is likely nothing more than a stylistic choice and the recurve itself on these blades (86s, 97s, 98s), though enough to catch the eye, is barely perceptible in use or even sharpening. Though I have sharpened my 97s more frequently than my 86s, I have had zero issues getting a good edge on them.
Typically, I do not like recurves on knives smaller than something I would use to delimb a tree. In this case though, it is subtle enough to not be a bother at all - which tells me it is just a style thing.