Why is this "not a simple A/B test"? It seems to be functionally the same (maybe A/B/C/etc. and not A/B), just with no actual product.

Is it the nonexistence of a real product which bothers you? Is it the comparison testing?

More generally, what do you feel constitutes an experiment that requires informed test subjects? I agree with you that there are shades of gray, but I feel the distinction likely lies somewhere between "red vs green button on landing page" and "new cancer drug," while you seem to be arguing that the former should still require informed consent. (Which could be a reasonable argument! But I'm trying to get a better gauge on what it is that you're saying.)