Let's you register an easy to remember domain name linked to an IP address you specify. It's useful for self hosting or avoiding having to buy a domain name.
Free version makes you confirm every month that you still want the domain name, but that's just a couple of clicks from the email they send you.
All your points are valid, but I'm not going to put in 3rd party hardware and their default slicer seems great to me. There's a group of users for who this is all more or less not an issue.
My Bambu had also been soooo easy. So there's that.