What's a job?
J/k aside, I own my own business so, I'm going to share from the other side of perspective.
I believe it can be useful for those who are looking for a job.
When I hire someone, my questions basically surround how much of my problem can you solve for me? The more problems (or % of the problem) one can solve, the better chance that person has of getting hired.
That's why for people who I know that they would never start their own business, I've always recommended them, continue to invest in yourself. The more problem you can solve, either vertically or horizontally, the better the chance you have at getting a job.
Going vertically, make you an ideal candidate for long term employee. Because your expertise matters. Going horizontally, makes you an ideal candidate for management material since if you know every aspect of the company, then managing them should be easier.