Yes, it is likely that many teams are better off joining FRC after participating in the other programs for several years.
One of the rookie teams I saw last weekend had worked their way up through FLL and VEX. They had a more thoroughly engineered robot than most of the other teams and were the only rookie team that could reliably score multiple game pieces in each and every match. They were the first pick of the first seed. They could actually do a credible job of mentoring other rookie teams because they had learned how to study the rules, develop game strategies and how to build and drive robots through those other programs.