But who says it hasn’t been? One of the things I enjoy in the world is “parallel thinking” when 2 people who have no contact with each other have basically the same idea at the same time. Just one silly example is that Steely Dan was negotiating their new record contract to be a band in name only (no touring, no real set membership, just the 2 head guys bringing people into the studio) in New York at almost the exact time Alan Parsons was shopping a studio only “band” around the record labels in London.
I find these parallel things interesting because there’s no good explanation. So one possible, no worse than all the others, explanation is time travel. Maybe Steely Dan didn’t do that, but Alan did, and then some time traveler knowing what happened to Steely Dan in their 2nd contract and how Alan Parsons Project worked, went back in time and met up with Donald Fagen in a bar and said “you know what would be cool...” And now we have Aja one of the greatest albums ever.
But new technology can not be kept secret forever, eventually, the technology gets out. When something is ready to be invented it will be invented. And it wouldn’t be small one off’s like your example, everyone from the future for ALL of eternity of the future would be traveling back in time as tourists.