Who benefits from this? Even though Let’s Encrypt stresses that most site operators will do fine sticking with ordinary domain certificates, there are still scenarios where a numeric identifier is the only practical choice:
Infrastructure services such as DNS-over-HTTPS (DoH) – where clients may pin a literal IP address for performance or censorship-evasion reasons.
IoT and home-lab devices – think network-attached storage boxes, for example, living behind static WAN addresses.
Ephemeral cloud workloads – short-lived back-end servers that spin up with public IPs faster than DNS records can propagate.
Domains need to be registered annually and DNS servers are needed to route traffic to them. But using an IP directly, you don’t need to worry about domain registration issues that can brick your systems, and you don’t have to worry about DNS providers knowing about your traffic (or maintaining your own private dns).
If it’s not a user trying in a memorable domain, an IP serves much better.