CLIA is the marketing arm for the cruise industry, and they do a good job of marketing. They do offer the accreditation for travel agents, and that is way better than using totally untrained agents.
However they have no regulatory control over any travel agent members. That is the biggest issue I have with the industry; with the exception of laws of the land, there is no regulation or oversight of travel agents.
In fact there are travel agencies that are members of CLIA which employ both/either inside and outside home based agents who are not even CLIA accredited.
Despite that, for years I've recommended using trained travel agents over booking direct with the cruise lines every time!
The problem is too many people stumble onto the bad ones, and are then driven to book directly with the cruise lines.