This isn't necessarily true. I had a 2.9ish GPA as an undergrad history major but I still got into a respectable engineering masters program (NC State) based on career merits. Granted, that was 10 years after I entered the workforce as a technical professional, but even so, there are many ways to reach any given end state, via hard work, excellent communication skills, and [hopefully] a strong network.
With excellent communication skills, and hard work, AND a strong network, you could get very far anyway.
Matter of fact those are 3 skills that are always in demand because anyone who possesses them can avoid truly coming to grips with the question in this thread: The necessity of good grades in determining your career.
