Yep, this is also true for dyndns curl/wget/fetch, have a look at the /docs on other special things that we can do except those. there is a larger functionality base here that I try to cover and not only (but including) curl/wget/fetch.
I run dynip.dev, there are like dynip . com that is retired, then there is dyndns and 100 different players i am sure, I am looking out to see if this is good, can be better or useless to the general public.