For the company? With your argument, maybe not.
But for the cadet, it’s invaluable. I could go on and on as to reasons why, but as somebody from Schuyler, who did 2 training cruises and 1 cadet observer, it is absolutely worthwhile for the cadet. And I didn’t even get a job with the company I worked for. Who happens to be the same company Midshipman X worked for.
In my opinion, the best training regimen would be what I did - a mix of training ship and cadet ship. But not everyone feels that way.