I have used dynamic dns for around 20 years, I think. But I have always used dyndns.com which these days seems to want to call themselves dyn.com. And some years back they were bought by Oracle, the kiss of death, and now they are impossible to deal with, arrogant, unsupportive, insular – all the things I expect of Oracle.
And why have I kept using them? Because that is what the routers supported. Dyndns was there first, and the ubiquitous linksys and netgear routers usually have a feature to do automatic updates for dynamic dns, but (often) the router will only update dyndns: nobody else. And I’ve got routers installed in various people houses that are doing this.
But I recently added a new house that I support, and that person has a proprietary and ponderous comcast router, which will barely do anything useful, and has no facility to update dynamic dns.