There are a lot of projects that involve very little of high level experience and a lot of grinding things. Juniors can be very good at these, and there are probably enough micro-problems that aren't critical that their brain is still being used and they're gaining skills that will help them take on more complicated tasks.
Something I last worked on with a junior engineer was our in-place backup system. I designed it and wrote the tricky part that involves DLL hell in a docker container. He wrote the "list backups", "delete backups", "create backup" CRUD API and CLI. My time was then free to put out fires or design something new.
It's not necessarily a no-brainer to hire and mentor junior engineers like the article says, but it's something you should think about. You will be surprised how much people actually know at job #1, and how quickly they can take on more complicated work that pays back your time investment in their mentorship. Plus, someone probably trained you to get you to where you are today, so there is some fairness in continuing the cycle.