The switch of car sound systems from a discrete unit that used a standard DIN form factor and connections to an integrated part of the dashboard from the mid '90s onward (and now into the complex "infotainment" system) kinda killed it as well. You can't just grad a single box out the dash and run. Does mean that car stereos are either un-upgradable, or require 3rd party kits to replace chunks of the facia nowadays though.