I am sure there are good reasons for it, the postgres proposal for switching concurrency models[1] comes to mind. I actually just posted this question to see what people come up with: https://news.ycombinator.com/item?id=36646299

My knee jerk reaction to rewrites is so negative I actually would like some counter evidence on when it worked out.

[1]https://www.postgresql.org/message-id/4658520e-5cd0-6242-e54...