I think their point is that you eat clutch when you slip it e.g. when you’re getting in and out if parking on hills, or in city stop and go traffic. When the clutch is fully engaged there’s little wear even hard-driving, and doing a straight in-and-out does not bother clutches much.

Hence Quattroportes eating clutches like nobody’s business while the harder-ridden higher-power Ferraris don’t.

As such downshifting would not wear clutches much.

And anecdotally I’ve never suffered from or heard of engine braking causing clutch issues.