There are those who would say that a dan (belt) ranking was indicitive of a modern (gendi) martial art - that koryo (traditional) ryuha did not award "ranks".

We offer an Excerpt from an interview with Takeda Tokimune by Stan Pranin:

"Did Sokaku Takeda Sensei give dan rankings?"

"No, he didn't. I started giving them. Sokaku awarded transmission scrolls called mokuroku, ogi, and kaiden, but it's quite a lot of work to write and present such scrolls. So now we give out dan ranks, not scrolls."

While those folk might tend to admomish Tokimune Soke for "giving in" to the modern way, it was pure economics that drove the decision, and practicality has always been a halmark of classical martial systems... at least those that survived...