I've never even heard of pyproject.toml and I open github projects behind packages to vet them (to a minimal degree, but still, making sure it's not a typosquat and still maintained and often also reading a bit of source code) on at least a weekly basis. It's not always python of course, but often enough. Maybe it's just some freak coincidence that I somehow never saw it or just don't recall while really it's mostly everywhere, but this broad statement for something I've never even heard of makes me think of JavaScript and the 'standard framework' that changes every six months.