It’s easy to forget how awful TLS was before Let’s Encrypt: you’d pay per-hostname, file tickets, manually validate domains, and then babysit a 1-year cert renewal calendar. Today it’s basically “install an ACME client once and forget it” and the web quietly shifted from <30% HTTPS to ~80% globally and ~95% in the US in a few years.
The impressive bit isn’t just the crypto, it’s that they attacked the operational problem: automation (ACME), good client ecosystem, and a nonprofit CA that’s fine with being invisible infrastructure. A boring, free cert became the default.
The next 10 years feel harder: shrinking lifetimes (45-day certs are coming) means “click to install cert” can’t exist anymore, and there’s still a huge long tail of internal dashboards, random appliances, and IoT gear that don’t have good automation hooks. We’ve solved “public websites on Linux boxes,” but not “everything else on the network.”