True, but the 70s was sort of their last hurrah. I remember Julia Child had a story about being served gelatin salad at a luncheon party in California, after she’d lived in France. IIRC it was one of the reasons she decided to wrote her cook books.
Gelatin salads and desserts make sense in Edwardian cuisine, where if you make them authentically they’re a real way to show off culinary mastery. After going through the “just add water and stir” processed food revolution, they become the culinary way sign for lazy, pinchbeck cookery.