Yeah I agree that when parallel construction happens they make the parallel case a logical one. But that involves making a parallel case. You're saying that the shirt -> Etsy -> Poshmark -> Linkedin chain was not created in that order and was created in some other order. I don't see how it's logical that it could be created in some other order, even with illegal evidence.
Beyond this specific case, I think the point of parallel construction is an interesting one because it makes it really difficult to know the "truth" where law enforcement have significant control over the flow of information.
Sometimes traditional or other media can help with the information asymmetry but sometimes, perhaps, not.
This is as opposed to say a police officer pulling over a drug dealer's car full drugs for failing to use a turn signal. If we assume illegal evidence was involved there, it's most logical the police were given some heads-up that there would be a drug dealer with a car full of drugs in the area to pull over, and the failing to signal on a turn was just used as a convenient excuse.