Getting into senior management probably means, for them, the end of their careers as bench scientists or working engineers. But, if you don't, line and staff realities are vital. Knowledge is power. As for climbing the organizational Everest, some will be happy with a success far short of the summit, while some will be determined to reach the top. But one way or another, as you plan your career, you need to know all about the business of staff and line.
Most organizations have two paths.
Both play an essential role in the work of any organization. If you're selling consulting services, for example, your consultants are line. If you're producing widgets, line divisions include sales, production, division and group operating executives. If you're human services, the line jobs have client or patient contact. Line positions always include the chair, CEO, president, chief operating officer and general manager of an organization.