Yeah the WF isnt strictly a Next Action list since you cant 'do it'. But it is whats next on that project. Its a marker giving you a reminder about the next step.
Since it exists at the same level (mostly) as a Next Action - i.e. its runway stuff, rather than 10K or 20K+ it makes sense to be able to review the WF against your Next Action lists. I find it helpful to be able to review WF lists at the same level and at the same point in my weekly review as emails/phone calls and so on.
But like all these things - there's no right, other than what works for you.