The progression through Associate Consultant, Consultant, Senior Consultant, and Principal Consultant may mean someone has been a consultant for a long time.
The progression of job titles may be because the consultant has developed as a professional. It may be because the employer wants to retain the talent. Who knows, the fancy job title is offered to boost the consultant’s ego/self-esteem.
Seniority, proficiency, talent, and skill is the factor of how much (and well) we have learned during our working life. It is not a factor of our years of experience.
So, let us not judge project resources by their job titles. Job titles are delusional!