Oldsmobile has some really terrific engineers. I know because I attended schools in the Lansing area with their kids. What killed the brand was a series of general managers in the late nineties and early two thousands. Until then Oldsmobile outsold Pontiac and Buick.
This is basically the story of GM for the last 40-50 years as a whole. The engineers will do or propose something brilliant and really great, and then management repeatedly snatches defeat from the jaws of victory. Saturn was another extremely good example of GM building something excellent and then their management just completely drove it off a cliff. The S-series was a really great design when it came out, and was honestly far better than it's internal competitors (like the Cavalier) and was competitive with small Japanese cars; the space frame, plastic panels, lost foam casting for the block, etc were really good engineering, and the car and brand had a deserved cult following. GM didn't like the fact it made the Cavalier look like shit and so naturally it was allowed to wither on the wine and then basically everything else after was just more badge engineered Chevy and Pontiac vehicles. GM's entire management should have been totally shitcanned at multiple points during and after the early 90s for the absolutely abhorrent job they did.