Quoted from pinwiztom:
But the vast majority of the audience has not seen, let alone played or heard a EM pinball machine
with bells and chimes in over 40 yrs,
so basically anyone under 50 would not be familiar with said vintage pinball sounds.
Ironically, probably they're aware of what a pinball machine sounds like, not based on playing actual pinball machines, but rather seeing pinball machines represented in movies/shows/cartoons. So despite not ever having played an EM, SS, DMD, whatever, they associate the bells and dings with that weird game they saw on an episode of Happy Days, Spongebob, etc.
So for them to associate with the sound, it has to be the generic bells/dings they've heard for years without even knowing it. And therefore we're stuck with the EM sounds for all eternity.