Why do people not realize Miami can add 3-4 more quality players even after signing Miller?

For some reason even NBA ysts did not mention the exemptions every team have which allows them go over the cap. If we get Mike Miller, we still have 7 mil to add 2 key free agents like Shaquille O'Neal and Raja Bell. We can then use the mid-level exception on an Allen Iverson or Tracy McGrady. Use the Early Bird rights to sign Haslem even if we go over the cap and just sign the 3 2nd rookies to the minimums without going over the luxury tax.