> It seems that this would never work in a fast moving and fast scaling environment A fast moving environment by definition would never even consider mainframe

> It seems that this would never work in a fast moving and fast scaling environment A fast moving environment by definition would never even consider mainframe computing. And most places who would consider mainframes are already at whatever scale they will be at the conceivable future. I used to work for a public healthcare company in the US that used mainframes extensively and when I was there we legally couldn't open any new locations. The only way to grow the business at all was to acquire existing ones, a multi-year process. So any changes or integrations typically had 12-18 months of lead time, and this was after everything was negotiated and signed. We typically heard about it a few months before that so sometimes up to two years. And as you can imagine with the amount of red tape and regulation around healthcare, and the requirements around being on the stock exchange, change control was a pretty arduous process.