Opus Dei is about acquiring power and money in both the secular and religious worlds.  They me describe themselves as lay organizations, but you can bet they all have total clerical control in every aspect of their lives.   And a personal prelature was an invention of JPII the Great Enabler for Opus Dei that gives them a status totally unheard of in the entire history of the church.  For any group to have total and complete independence of the local diocesan bishop is unheard of in the entire history of the church and undermines the authority of the bishop.