Older standards typically have a larger pool of people who can contribute because the standard has been around longer.

A programmer might have more experience with an older standard due to the length of time has been out or because the toolchain they use elsewhere (personal projects, embedded comes to mind, or work) hasn't updated to the new standard.

Coming up to speed with the new standard is not free. The tooling may be free for the most common targets (embedded usually lags), but taking the time to learn isn't free.