Depends on what you mean by "routinely." In 2020, the last year that the annual survey published these numbers, 8.7% of Rust programmers used exclusively nightly. It has been dropping every year.
Some people do occasionally use nightly; at my job, most code is on stable, but there are a few projects that do currently require a couple of nightly specific things.
>There are teams out there already with many years of Rust experience in practice.
They routinely use nightly version, no?