Many of these "new-feature enthusiasts" work at companies like Google and Meta where they have both enormous C++ codebases and dedicated teams that constantly w

Many of these "new-feature enthusiasts" work at companies like Google and Meta where they have both enormous C++ codebases and dedicated teams that constantly work on internal libraries and tooling to make those codebases better. They will be using these features because they can mandate it. Some big new C++ features reflect this reality, for example coroutines: it's not a feature you would use directly as an application developer, but it provides sufficiently flexible underpinnings that allow these FAANG teams (and other library developers of course) to integrate coroutines into their existing async libraries and start converting code over.