I'm not all together sure that's an accurate assessment.
My initial goal with my student's, is to make them qualified to test for Shodan. Once they have that yudansha ranking, it's my hope, that they continue their study and improve upon what was shown to them. The desire for higher rank, is not something that I promote.
Once a student has received their Shodan, they (either) begin training to better understand what they've been shown (and thereby become more proficient at it), or they quit.
Surprisingly, the majority quit. At least of those that even stick with it to their Shodan test. Most will quit at brown (3-1st kyu). Whatever motivated them to begin their study, evidently dissipated.
Once that rank has been attained, a student's eye's are commonly opened (to a lot of the BS attached to rank in general).