My best guess is that its made for the lower end of tech user, who knows they want to ssh but doesn't know enough to be able to do it securely on their own? Otherwise I have no idea what the use-case is
Most of us on HN use our own VPNs, or have a dozen other ways to get at infrastructure from anywhere (and mosh, as others have suggested, is a better alternative for simple shell access over high-latency flaky connections)... but there are a _lot_ of people who don't want to (or couldn't figure out how to) maintain their own VPN. Or they want to deploy Pis at remote sites and each one has a weird and unique networking config, and they don't want to mess with Tailscale or the like.
It's a useful service, but it's not supposed to compete with homelabber setups, or enterprise solutions. At least I don't think so.