The 5 stars of ratatouille might have been an anachronistic shorthand of good quality based more on how so much of what the average person is familiar with is a 5 star rating system (think product reviews on Amazon, app reviews on Google play/app store, driver ratings on Uber etc)

Like, I imagine people have an understanding that Michelin stars are a thing but don’t know what those stars mean other than more stars is more gooder. And to muddle it up even more in the present day a single chef can have more than 3 stars because that chef owns multiple restaurants. (See British shouty chef’s 17 Michelin stars)