Agree to an extent. Contractor relationships are abused at many companies, but this is usually the case with mid to low level positions. People who make it through senior ranks and go on to become consultants get treated very differently. The latter is also incredibly lucrative.
Can confirm. Senior consultants are also very valuable to companies because they can say and do things that are necessary but politically taboo within the organisation. - Like pointing out underperforming teams and managers to upper management.