They way I've set things up at my current company is this:
When a developer creates a pull request an ephemeral (preview) environment is generated.
When that code is merged it automatically gets deployed first to our staging environment and then immediately to production.
Staging gets a sanitized copy of production's data every night so both the code and the data are close mirrors of production and that's what developers (and those preview environments) integrate with when they're calling services other than their own.
If you were to get rid of staging would you stand up your entire backend every time you made a preview environment? Does that include replicating databases or would you just use seed data that may or may not resemble what's in production?
It seems like the solution they're pitching works great if you have a small team and only a few services/sites.
I work in tech, but thanks to some stubborn drive for creation my parents instilled in me, I also make music. And honestly, compared to music, even the advertising industry feels cutting-edge. Music is still operating with one foot stuck decades in the past.