Great piece. In fact, this is another big topic. I can't image a bank switching technology in a such easy way for components that maybe are critical.

A technology switch can have multiple sides, sometimes the success is way beyond expectations and the current implementation doesn't fit the real requirements, making the switch looking more to a success rather than a failure. On the opposite it's very common to have the exact same problem you described, new trending technology picked, hit the limit, switch to and old more robust solution, this is definitely a failure and is something managers don't like.

I faced a similar problem with Mongo 2 years ago, had the same switch to PostgreSQL.