There's always been a notion that if we could emulate the lives of those we admire, then our lives would have the same outcomes as theirs – talented, successful, rich, famous, happy, whatever. That, of course, explains all the "Seven Secrets of…." books and the popularity of biographies as treasure maps to our desired fortunes. Although the lives of successful music artists fall into that same category and there are certainly crafts and skills to be mastered, there are two areas that cannot be duplicated, which are, unfortunately, the two most important things required for success – artistry and luck. Which is why nothing compares to Prince. His was the perfect storm of skills, artistry and luck.
If you're a self-built artist, the label could be using you for what you've already created. If you've got a huge fanbase already, millions of YouTube plays, and have cracked radio, a label deal can't offer you much more.
You have the potential to be shelved. If the label doesn't think you've got what it takes, they have the option to do nothing for you. Not to mention, your deal prevents you from doing much without them or their approval.