One of the most important "con"'s is that without controls, fewer people will allow their data to be included in the data sets.

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Cynddl 4 hours ago | parent [-]

That's a very important point. The people who opt out first are typically not a random fraction of the population, and this makes it much harder to make any analyses with the resulting datasets: it gets very hard to know if your analyses are representative of the population, or not.

	▲	tptacek 4 hours ago \| parent [-]
		This is why it was such a big deal when that researcher at Cleveland State misappropriated UKBB data for a race-science study with Emil Kirkegaard. After he was fired, people on Twitter were all like "this is just suppression of science", but the reality is that what they did, contravening UKBB rules, constituted potentially an existential threat to the whole program.