>>less healthy fat sources — particularly full-fat dairy products and butter

There's some association with fewer CVD events with full fat dairy vs nonfat. See this study in PLOS (done in Sweeden where there’s a high level of dairy consumption). There might be a confounder in what, exactly, was used as a butter substitute. I’ve seen some TPN (tube feeding) work showing higher CVD/mortality rates with corn oil. Ditto with situations where nutrition is controlled (mental hospitals). I don’t think any would pass board approval these days, so I’m not expecting any do-overs.

That said, I’ve been convinced that the health effects from olive oil are twofold. First, monounsaturated fatty acids are less susceptible to oxidative damage — and dietary fats (along with the stearic acid, a saturated fat, that we make internally) end up in cell walls. And second, oleocanthal is anti-inflammatory BUT it’s only present at any quantity in extra virgin olive oil — and the quantity is quite variable depending on varietal, growing conditions, ripeness at harvest, how much delay before the oil is extracted. There don’t seem to be any studies on olive oils that control for oleocanthal, so it’s an uncontrolled variable. About the closest I’ve seen is a study in which EVOO had better result than non-EVOO — with no regard for oleocanthal levels — but we know it’s less present in non-EVOO, so it fits the anti-inflammatory hypothesis, but it’s not strong evidence.