You’re only thinking of public use cases. For personal use, as I’m sure most people self-hosting would be using it for, it’s very convenient. I use it for work for typing long urls into a new computer we don’t yet have remote management of yet. At home, it makes it really easy to type any link with a TV remote or controller.

I’ve heard DuckDNS has become more unreliable. You could try another service like afraid.org and see if it makes a difference.