No they didn't. There's no evidence whatsoever for that and people keep repeating it as if it's true.
The only thing remotely close to what you're describing is when they implemented PBR in around 2015 which is a more flexible rendering system, but lots of games were doing that at the time without having to start from scratch.
(A lot of this misinformation is probably my fault, because what did happen is that they had to scrap a lot of the assets they were using, and I was one of the few people who knew about that so I kept talking about it. But people misinterpreted that as having scrapped the entire game, which is ridiculous.)