lol
Yes, reef hobbyists may be the first to discover a biological role for barium. That idea seems highly unlikely to me, but, of course, cannot be proven incorrect without waiting to see if it happens. It hasn't happened yet.
However, the world of trace elements is not nearly as simple as some ICP folks and supplement marketers would have you believe.
Trace elements vary greatly by location and depth. What exactly are you matching? Some ICP companies and supplement manufacturers specifically set targets that do not match seawater. Magnesium, for example, is often boosted far above natural levels.
Even more complicating, a certain concentration of, say, iron, says almost nothing about it bioavailability to organisms, so while matching some seawater concentration may be worthy, if you ignore the chemical form present, you will have failed to match its bioavailability. Bioavailability is impacted to a large extent by the oxidation state and the binding of the ion to organics of various sorts, some of which decrease bioavailability, some of which increase it, and some of which only increase it for specific organisms that are designed to bind that specific organic-bound form (such as by releasing siderophores that go out, scavenge iron, then are selectively taken back up by some organisms).
We also learned the hard way over many years that matching natural levels of phosphate and nitrate was not optimal in many reef aquaria. Why would trace elements be different.?
So while it sounds simple and obvious to match seawater, in reality, it is far from easy, and may not be optimal.
That said, I have no problem with folks maintaining ions I think are useless. I just have a problem with folks indicating that one needs to do those to have optimal success, since I am confident that not a single test has been done on two matched aquaria, one with and one without barium dosing (or whatever ions, strontium, rubidium, etc.) , to see if there's a difference. That, IMO, is the best way to show an effect, not maintain 15 things, and claim that because it works it is desirable to maintain all 15.