I would also point out that “legally authorized representative” in this phrasing refers to people who are legally designated as a representative of the subject, and not the admin of the site in question.

Right, sorry. I understood it meant legal guardian in the other contexts, but misread this line in particular

For example, this is how Indiana University guides researchers for making exempt determinations when reaching out to their IRB. University of South Carolina's IRB provides explicit examples.

Again, you are posting links that tell me that the type of research done by Reddit and Facebook would not be covered. "Exempt" in these links means exempt from the full scope of requirements of the Federal Policy for the Protection of Human Subjects for research that presents no more than minimal risk and falls into one of one of predefined categories. "Exempt" research may still require informed consent. Your prior link was for exemption to informed consent specifically. In my view, the Reddit experiment satisfies neither the conditions for "exempt" research nor the conditions for "informed consent exemption".

It may be hard to keep track of all the legalese flowcharts, all the AND and OR conjugated lists of preconditions, but I think I got it right. To take a look at UCSB flowchart for example, how would I argue that my Reddit-like experiment is "exempt"? I would still need to meet with the IRB to determine whether that my research is exempt in the first place (Reddit Inc has no IRB), and to do so I'd have to show that ALL of these are true:

• meets the definition of “research”
• meets the definition of a “human subject”, such as involving collecting data about living individuals
• qualifies as no risk or minimal risk to subjects

Then I would pick a predefined category, probably Exempt Category 3 - Benign Behavioral Interventions with Adults, and show that I meet at least ONE of these is preconditions:

• a) information obtained is recorded in such a manner that human subjects cannot be identified, directly or through identifiers linked to the subjects
• b) any disclosure of the human subjects' responses outside the research could reasonably place the subjects at risk of criminal or civil liability or be damaging to > the subjects' financial standing, employability, or reputation
• or c) information obtained is recorded in such a manner that human subjects can be identified, directly or through identifiers linked to the subjects and if the IRB conducts a limited review for provisions for protecting privacy and maintaining confidentiality.

Embarrassingly, b) is probably a typo, since on every other site the language used is that the responses would NOT reasonably place the subjects at risk of criminal or civil liability, but whatever. Assuming we want to keep track of as much PI as possible (whether or not you agree that any username-related information online is PI at all), we'll take the (corrected) option b) since there is no criminal liability for the user from our experiments. Then we have to follow all of these example rules:

• This category does not include minors.
• Benign behavioral interventions must be brief in duration, harmless, painless and not physically invasive and there is no reason to think the interventions will be offensive or embarrassing.
• Interventions should not have a last significant adverse impact on the participants.
• Research involving deception is allowed if the participant is prospectively informed, and agrees to, that they will be unaware of, or misled regarding the nature or purpose of the research.

Reddit violates ALL of these example rules.

• minors use reddit and there is no indication that reddit experiments exclude them. Minors are not prohibited on the site and there is no tracking of age other than the vague "show me NSFW results" checkbox
• intervention is not brief, has lasted a week or more
• intervention is not harmless, user was definitely made upset by being blocked from mobile web for no reason
• intervention definitely embarrassed the user, making them think they are dumb and doing something obviously wrong, and there was ample reason to expect this outcome
• intervention had a lasting adverse impact on the participant, both in being unable to use reddit itself for no reason, and in them thinking about the mysterious problem for days to the point where they go online to complain about it - much different reaction than from say somebody playing Yakety Sax in your ear while you try to solve math problems like in the example below
• the subject was deceived and was definitely not informed prospectively that deception may take place, neither has agreed to it; subject was not informed even retrospectively other than some random admin suggesting they were part of an experiment after they complained online; for that matter the subject was not informed that an experiment would be taking place at all and has never agreed to anything, other than possibly in the ToS.

So you see, even your own examples of specific IRB guidelines disagree with you.

The examples of research listed under Category 3 are:

• A random assignment of participants to take a test under various noise conditions.
• A study involving randomly assigning participants to various experimental conditions where they decide how to allocate cash between themselves and others.

The Reddit experiment goes beyond these, as it is designed to specifically manipulate the user's emotional state, to deliberately frustrate the user to see whether they would download the native app or abandon reddit entirely when their web access is blocked. It is much more similar to the Facebook shadowbanning experiment (which you agreed can shove it) than to these examples above. I'd say the level of frustration and embarrassment is similar to the Asch conformity experiment, which if you wanted to repeat it now I was taught under modern rules DOES require IRB review, DOES require informed consent (if not with details of the deception then at least with the very fact that an experiment is taking place), DOES require post-experiment debfrief, all because it DOES present a risk of causing emotional harm.

Can you find instances of modern Asch experiment research papers that specifically show they are "exempt" research and/or that have received an exemption from collecting informed consent prospectively and/or retrospectively? If you do, it will help convince me that that's how modern research ethics really works.