I think this website predates the widespread support of will-change, the website first displayed this parallax effect (in a more primitive way) sometime in 2014.
caniuse.com tells me the first moment that both Firefox and Chrome supported this property was in early 2015.
Interesting. Is it possible that the addition of `will-change` caused browsers to relax their default heuristics, believing that websites would use the property as needed now that it's available?
caniuse.com tells me the first moment that both Firefox and Chrome supported this property was in early 2015.