Adding the correct blur to motion makes it appear clearer but seen as a still, it's obviously not clearer. The nuance is correct motion blur appears clearer while guaranteeing it's as clear as the human visual system can perceive moving details at that speed, so no perceptual detail is actually lost. It's a method that objectively improves perception which only works in motion. If frozen, the method breaks. Thus, evaluating motion blurred stills for clarity or interpretability is incorrect.
The rest of the article focuses on details of proper implementation while missing the opportunity to question whether some of these animations should exist at all. IMHO, motion can be a valuable affordance in limited doses but it's reached a point of overuse and, in some cases, outright abuse of the user's visual field and cognitive load. Designers (and their PMs) see it as a badge of 'Refined Modern UX' but it's devolved into a trendy gimmick aping good design without being good design.