Very interesting point. Looking at that bit of history, I think it's correct to say that Yamaguchi attempted a 3A in practice and 3Lz+3T really only because of Ito, but I'm not so sure about Harding. Would Harding had landed the first ever 3A then, along with the other accomplishments with the number of triples in a single program?If she had been competing in the IJS system someone else would have had to do that though-- it's like the idea that you're standing on the shoulder of giants.
And then we mostly had an "artistic" revolution in skating, with some landing difficult +3Lo combos, and some others trying +3T combos. If Harding still goes for her content, then I think this technical development still happens. If we think Ito would have started competing as a senior in 2004-05, she'd still have the opportunity to establish herself with a quad in seniors, and even get a rotated quad in juniors before Ando - and that's assuming someone like Ando would even be skating if Ito hadn't happened to be a world champion.