Because you could have 50 subdomains, for which you'd need either a wildcard cert or 50 separate certs. That might seem like a ton per week, but consider a Paa

Because you could have 50 subdomains, for which you'd need either a wildcard cert or 50 separate certs. That might seem like a ton per week, but consider a PaaS (example-123.herokuapp.com) or a blog platform (example-diary.someblogapp.com). Personally I'd prefer a wildcard cert there, but at organizations where certificate inventory is a requirement (where they need to track, procure, and invalidate on a per-subdomain basis) Let's Encrypt is a solid option.