Yes, I know that the augmented maximum "covers things stacking" by giving a maximum that they can stack up to. But that's not what I'm talking about. I was talking about a rule that covers the use of duplicate items to reach that maximum with little effort.
Multiple suprathyroid glands, trying to use two medkits, taking enhanced articulation multiple times, and other things like that. These (to my mind) fall into a category where common sense should tell you that these don't work. However, the rules never explicitly deny them.
In my opinion, datajacks fall into a similar position. The wireless bonus is that the implant allows you to use the augmented person's body as a makeshift grounding wire which helps mitigate noise. Having more than one datajack wouldn't make that any more effective. This is my "head-cannon," which is what feeds into why I have this stance. That reasoning sort of explains why nothing needs to be plugged into the datajacks to benefit from the wireless bonus. If I wanted to make the item make even more sense, I would probably require the device to be plugged in directly to the datajack. Then the issue would solve itself, because only one device could only be plugged in at a time, and multiple datajacks would have the benefit of applying the bonus to more devices.
Notably, I've never run it as multiple datajacks stacking, and I've never seen anyone attempt to do so. In the last several years, since the start of 5th edition, it has never come up in any of the games that I've run. So I've never met these Folks that have been doing it for years. Just because some people have ran with it that way, doesn't make it right. I've seen NPCs that have multiple datajacks, but all of them were "old-school" in some way, with the multiple datajacks being relics of the previous ages of the matrix where having multiple datajacks allowed you to connect to more devices at once. None of the NPCs that were built with multiple datajacks had any indication of having extra noise reduction because of them, so this can't be used as precedence.
And while Noise can be a fairly meaningless mechanic, I don't think there should be ways to simply make it laughably trivial. Just like Background Count, when used in the right way, noise can be an interesting challenge to deal with. The ways to get large amounts of noise reduction are fairly specific, usually with limitations of some sort. Just buying up a bunch of cheap implants doesn't seem like an appropriate way to deal with it. Particularly when Antenna cost the same amount of essence but don't stack infinitely. Datajacks do not exist solely for the purpose of noise reduction (its an added bonus), so why would they work better for that purpose than the cyberware that is designed exclusively to do it.