"Hot Module Replacement (HMR) is a feature in some programming languages and frameworks that allows developers to update modules or parts of the application in real-time while the application is running, without requiring a full page refresh. This is particularly useful during development as it speeds up the development process and helps maintain the application state."
This is not only about leadership style, but also founding. I don't know the current TS team, but I know its dozens of full time workers backed by microsoft, not only core devs, but community organizers, evangelists, etc. There is no comparison to an independent project.
Without this management style Elm would be the oppositive of what it is today
(simple language, very fast compiler, efficient tree shaking, no runtime exceptions) wanting to add at all costs Haskell features and JS direct sync interop.
Indeed the releases are less frequent and Evan works in batches to avoid breaking changes every year. But he didn't left, he still works on private branches and on security patches when needed. Yesterday he gave this presentation:
Elm is used in many medium/large companies. The biggest ones are NoRedInk and Vendr, the later reached 1B valuation recently with 600k+ loc Elm codebase.