I've been doing network security for twenty years, so I know what that is, this just sounds like some marketing and sales people started mashing buzzwords together.
DevOps is mashing development and operations together. But that ignores security, often putting security reviews after the code has been deployed or at least after it's done being written, which necessitates re-work. DevSecOps makes sure security is a part of the development and operations work.
Yes it's a re-wording of an existing concept. No, it is not a new idea. Yes, it is important enough to call it out because so many companies don't let security/operations/development work together.
You're not the target audience, your CISO or CTO is.
Whether a company has someone with the title "CISO" or not matters very little to how they design security into their products. The term "DevSecOps" is designed to eliminate the need for a discreet "security" workforce.
To answer the question more directly: I've worked with 10,000+ employee companies with no CISO and I've worked with <1,000 employee companies with separate CTO, CIO, and CISO roles. At the executive level, job titles are more of suggestions than strictly defined silos. It all depends on how the company is organized and what their strategic priorities are.
Common term in defense, basically just an organizational efficiency. Since the devops people kept breaking security, we made them sit next to the security people.
Yes it's a re-wording of an existing concept. No, it is not a new idea. Yes, it is important enough to call it out because so many companies don't let security/operations/development work together.
You're not the target audience, your CISO or CTO is.