Someone can master a subject in 5+ years if they do it everyday. A fullstack dev with 20 years experience can master all those stated and more and I know fullstack devs (granted not many) than can maintain entire apps like this.
The problem is that all of these are moving targets. You don't master DevOps in 5 years and then you're done forever (same with backend and front-end development), these are constantly changing fields that require continually honing your skills.
I'm a fullstack dev who is often our devops/kubernetes lead. I'd say over 50% of my day is around DevOps tasks, but I'm likely to write an API or hone a frontend animation as well. I contribute on all parts of our microservice based kubernetes government application, but do skew to the devops side where the rest of my teams' experience is lighter. I can write iptables or webpack configs, I can implement OAuth or modify bezier curves for animations, and frequently do it all at my job. I have just over 10 years of professional experience but have been programming longer.