In Consulting Services you have to work on client projects - most of the time. This is common knowledge. To be promoted one has to show up with performance (whatever this means), mainly on client projects, get proper appraisals and so on - so far, so good.
To become a Principal Consultant you need a proper consulting history, you need to express some minimum seniority (also in years of experience and relevance of experience), and overall there are some rules which are also officially communicated: you have to bring in business or at least perform as project manager for a while, be responsible for some minimum revenue, manage a team and of course you need to have and demonstrate relevant skills. These skills have to be related to the business such as subject matter expertise, methodology and so forth.
But if Capco promote people to Principal Consultant in high speed, who have nearly never been billable, nearly no important knowledge about the business, nearly no client project experience, who cannot really be seen as consultants at all, then this is going a beyond a joke. People who provide marketing material and support well in project proposals are truly useful but this is not consulting. Promoting those people to Principal Consultant - especially if you compare their profiles to those of other Principal Consultants - is inappropriate. This exceeds any tolerance regarding unfairness.