Yeah, I hear you. There's really no practical difference between saying 174cm and 17.4dm I think from the American perspective where 6ft is a sort of benchmark for adult male height, so psychologically that 6 looms large. CMs obviously work fine, but I'm trained to see the bigger 17 as a sort of benchmark/goal. None of that is healthy or rational, though.

Maybe it's easier to say "Oh, they're 17dm" or "15dm" and get a general sense for the height of a person. When you need to get precise, it's not useful.